Copyright (c) 1980, 1993
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
.bp .sh 1 "Common usage" .pp The .i Mail command has two distinct usages, according to whether one wants to send or receive mail. Sending mail is simple: to send a message to a user whose login name is, say, \*(lqroot,\*(rq use the shell command: .(l % Mail root .)l then type your message. When you reach the end of the message, type an EOT (control-d) at the beginning of a line, which will cause .i Mail to echo \*(lqEOT\*(rq and return you to the Shell. When the user you sent mail to next logs in, he will receive the message: .(l You have mail. .)l to alert him to the existence of your message. .pp If, while you are composing the message you decide that you do not wish to send it after all, you can abort the letter with a \s-2RUBOUT\s0. Typing a single \s-2RUBOUT\s0 causes .i Mail to print .(l (Interrupt -- one more to kill letter) .)l Typing a second \s-2RUBOUT\s0 causes .i Mail to save your partial letter on the file .q dead.letter in your home directory and abort the letter. Once you have sent mail to someone, there is no way to undo the act, so be careful. .pp The message your recipient reads will consist of the message you typed, preceded by a line telling who sent the message (your login name) and the date and time it was sent. .pp If you want to send the same message to several other people, you can list their login names on the command line. Thus, .(l % Mail sam bob john Tuition fees are due next Friday. Don't forget!! <Control-d> EOT % .)l will send the reminder to sam, bob, and john. .pp If, when you log in, you see the message, .(l You have mail. .)l you can read the mail by typing simply: .(l % Mail .)l .i Mail will respond by typing its version number and date and then listing the messages you have waiting. Then it will type a prompt and await your command. The messages are assigned numbers starting with 1 \*- you refer to the messages with these numbers. .i Mail keeps track of which messages are .i new (have been sent since you last read your mail) and .i read (have been read by you). New messages have an .b N next to them in the header listing and old, but unread messages have a .b U next to them. .i Mail keeps track of new/old and read/unread messages by putting a header field called .q Status into your messages. .pp To look at a specific message, use the .b type command, which may be abbreviated to simply .b t . For example, if you had the following messages: .(l N 1 root Wed Sep 21 09:21 "Tuition fees" N 2 sam Tue Sep 20 22:55 .)l you could examine the first message by giving the command: .(l type 1 .)l which might cause .i Mail to respond with, for example: .(l Message 1: From root Wed Sep 21 09:21:45 1978 Subject: Tuition fees Status: R Tuition fees are due next Wednesday. Don't forget!! .)l Many .i Mail commands that operate on messages take a message number as an argument like the .b type command. For these commands, there is a notion of a current message. When you enter the .i Mail program, the current message is initially the first one. Thus, you can often omit the message number and use, for example, .(l t .)l to type the current message. As a further shorthand, you can type a message by simply giving its message number. Hence, .(l 1 .)l would type the first message. .pp Frequently, it is useful to read the messages in your mailbox in order, one after another. You can read the next message in .i Mail by simply typing a newline. As a special case, you can type a newline as your first command to .i Mail to type the first message. .pp If, after typing a message, you wish to immediately send a reply, you can do so with the .b reply command. .b Reply , like .b type , takes a message number as an argument. .i Mail then begins a message addressed to the user who sent you the message. You may then type in your letter in reply, followed by a <control-d> at the beginning of a line, as before. .i Mail will type EOT, then type the ampersand prompt to indicate its readiness to accept another command. In our example, if, after typing the first message, you wished to reply to it, you might give the command: .(l reply .)l .i Mail responds by typing: .(l To: root Subject: Re: Tuition fees .)l and waiting for you to enter your letter. You are now in the message collection mode described at the beginning of this section and .i Mail will gather up your message up to a control-d. Note that it copies the subject header from the original message. This is useful in that correspondence about a particular matter will tend to retain the same subject heading, making it easy to recognize. If there are other header fields in the message, the information found will also be used. For example, if the letter had a .q "To:" header listing several recipients, .i Mail would arrange to send your replay to the same people as well. Similarly, if the original message contained a .q "Cc:" (carbon copies to) field, .i Mail would send your reply to .i those users, too. .i Mail is careful, though, not too send the message to .i you , even if you appear in the .q "To:" or .q "Cc:" field, unless you ask to be included explicitly. See section 4 for more details. .pp After typing in your letter, the dialog with .i Mail might look like the following: .(l reply To: root Subject: Tuition fees Thanks for the reminder EOT & .)l .pp The .b reply command is especially useful for sustaining extended conversations over the message system, with other .q listening users receiving copies of the conversation. The .b reply command can be abbreviated to .b r . .pp Sometimes you will receive a message that has been sent to several people and wish to reply .i only to the person who sent it. .b Reply with a capital .b R replies to a message, but sends a copy to the sender only. .pp If you wish, while reading your mail, to send a message to someone, but not as a reply to one of your messages, you can send the message directly with the .b mail command, which takes as arguments the names of the recipients you wish to send to. For example, to send a message to .q frank, you would do: .(l mail frank This is to confirm our meeting next Friday at 4. EOT & .)l The .b mail command can be abbreviated to .b m . .pp Normally, each message you receive is saved in the file .i mbox in your login directory at the time you leave .i Mail . Often, however, you will not want to save a particular message you have received because it is only of passing interest. To avoid saving a message in .i mbox you can delete it using the .b delete command. In our example, .(l delete 1 .)l will prevent .i Mail from saving message 1 (from root) in .i mbox . In addition to not saving deleted messages, .i Mail will not let you type them, either. The effect is to make the message disappear altogether, along with its number. The .b delete command can be abbreviated to simply .b d . .pp Many features of .i Mail can be tailored to your liking with the .b set command. The .b set command has two forms, depending on whether you are setting a .i binary option or a .i valued option. Binary options are either on or off. For example, the .q ask option informs .i Mail that each time you send a message, you want it to prompt you for a subject header, to be included in the message. To set the .q ask option, you would type .(l set ask .)l .pp Another useful .i Mail option is .q hold. Unless told otherwise, .i Mail moves the messages from your system mailbox to the file .i mbox in your home directory when you leave .i Mail . If you want .i Mail to keep your letters in the system mailbox instead, you can set the .q hold option. .pp Valued options are values which .i Mail uses to adapt to your tastes. For example, the .q SHELL option tells .i Mail which shell you like to use, and is specified by .(l set SHELL=/bin/csh .)l for example. Note that no spaces are allowed in .q "SHELL=/bin/csh." A complete list of the .i Mail options appears in section 5. .pp Another important valued option is .q crt. If you use a fast video terminal, you will find that when you print long messages, they fly by too quickly for you to read them. With the .q crt option, you can make .i Mail print any message larger than a given number of lines by sending it through a paging program. This program is specified by the valued option PAGER. If PAGER is not set, a default paginator is used. For example, most CRT users with 24-line screens should do: .(l set crt=24 .)l to paginate messages that will not fit on their screens. In the default state, more (default paginator) prints a screenful of information, then types --More--. Type a space to see the next screenful. .pp Another adaptation to user needs that .i Mail provides is that of .i aliases . An alias is simply a name which stands for one or more real user names. .i Mail sent to an alias is really sent to the list of real users associated with it. For example, an alias can be defined for the members of a project, so that you can send mail to the whole project by sending mail to just a single name. The .b alias command in .i Mail defines an alias. Suppose that the users in a project are named Sam, Sally, Steve, and Susan. To define an alias called .q project for them, you would use the .i Mail command: .(l alias project sam sally steve susan .)l The .b alias command can also be used to provide a convenient name for someone whose user name is inconvenient. For example, if a user named .q "Bob Anderson" had the login name .q anderson," you might want to use: .(l alias bob anderson .)l so that you could send mail to the shorter name, .q bob. .pp While the .b alias and .b set commands allow you to customize .i Mail , they have the drawback that they must be retyped each time you enter .i Mail . To make them more convenient to use, .i Mail always looks for two files when it is invoked. It first reads a system wide file .q /etc/mail.rc, then a user specific file, .q .mailrc, which is found in the user's home directory. The system wide file is maintained by the system administrator and contains .b set commands that are applicable to all users of the system. The .q .mailrc file is usually used by each user to set options the way he likes and define individual aliases. For example, my .mailrc file looks like this: .(l set ask nosave SHELL=/bin/csh .)l As you can see, it is possible to set many options in the same .b set command. The .q nosave option is described in section 5. .pp Mail aliasing is implemented at the system-wide level by the mail delivery system .i sendmail . These aliases are stored in the file /usr/lib/aliases and are accessible to all users of the system. The lines in /usr/lib/aliases are of the form: .(l alias: name\*<1\*>, name\*<2\*>, name\*<3\*> .)l where .i alias is the mailing list name and the .i name\*<i\*> are the members of the list. Long lists can be continued onto the next line by starting the next line with a space or tab. Remember that you must execute the shell command .i newaliases after editing /usr/lib/aliases since the delivery system uses an indexed file created by .i newaliases . .pp We have seen that .i Mail can be invoked with command line arguments which are people to send the message to, or with no arguments to read mail. Specifying the .rb -f flag on the command line causes .i Mail to read messages from a file other than your system mailbox. For example, if you have a collection of messages in the file .q letters you can use .i Mail to read them with: .(l % Mail -f letters .)l You can use all the .i Mail commands described in this document to examine, modify, or delete messages from your .q letters file, which will be rewritten when you leave .i Mail with the .b quit command described below. .pp Since mail that you read is saved in the file .i mbox in your home directory by default, you can read .i mbox in your home directory by using simply .(l % Mail -f .)l .pp Normally, messages that you examine using the .b type command are saved in the file .q mbox in your home directory if you leave .i Mail with the .b quit command described below. If you wish to retain a message in your system mailbox you can use the .b preserve command to tell .i Mail to leave it there. The .b preserve command accepts a list of message numbers, just like .b type and may be abbreviated to .b pre . .pp Messages in your system mailbox that you do not examine are normally retained in your system mailbox automatically. If you wish to have such a message saved in .i mbox without reading it, you may use the .b mbox command to have them so saved. For example, .(l mbox 2 .)l in our example would cause the second message (from sam) to be saved in .i mbox when the .b quit command is executed. .b Mbox is also the way to direct messages to your .i mbox file if you have set the .q hold option described above. .b Mbox can be abbreviated to .b mb . .pp When you have perused all the messages of interest, you can leave .i Mail with the .b quit command, which saves the messages you have typed but not deleted in the file .i mbox in your login directory. Deleted messages are discarded irretrievably, and messages left untouched are preserved in your system mailbox so that you will see them the next time you type: .(l % Mail .)l The .b quit command can be abbreviated to simply .b q . .pp If you wish for some reason to leave .i Mail quickly without altering either your system mailbox or .i mbox , you can type the .b x command (short for .b exit ), which will immediately return you to the Shell without changing anything. .pp If, instead, you want to execute a Shell command without leaving .i Mail , you can type the command preceded by an exclamation point, just as in the text editor. Thus, for instance: .(l !date .)l will print the current date without leaving .i Mail . .pp Finally, the .b help command is available to print out a brief summary of the .i Mail commands, using only the single character command abbreviations.
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
.bp .sh 1 "Common usage" .pp The .i Mail command has two distinct usages, according to whether one wants to send or receive mail. Sending mail is simple: to send a message to a user whose login name is, say, \*(lqroot,\*(rq use the shell command: .(l % Mail root .)l then type your message. When you reach the end of the message, type an EOT (control-d) at the beginning of a line, which will cause .i Mail to echo \*(lqEOT\*(rq and return you to the Shell. When the user you sent mail to next logs in, he will receive the message: .(l You have mail. .)l to alert him to the existence of your message. .pp If, while you are composing the message you decide that you do not wish to send it after all, you can abort the letter with a \s-2RUBOUT\s0. Typing a single \s-2RUBOUT\s0 causes .i Mail to print .(l (Interrupt -- one more to kill letter) .)l Typing a second \s-2RUBOUT\s0 causes .i Mail to save your partial letter on the file .q dead.letter in your home directory and abort the letter. Once you have sent mail to someone, there is no way to undo the act, so be careful. .pp The message your recipient reads will consist of the message you typed, preceded by a line telling who sent the message (your login name) and the date and time it was sent. .pp If you want to send the same message to several other people, you can list their login names on the command line. Thus, .(l % Mail sam bob john Tuition fees are due next Friday. Don't forget!! <Control-d> EOT % .)l will send the reminder to sam, bob, and john. .pp If, when you log in, you see the message, .(l You have mail. .)l you can read the mail by typing simply: .(l % Mail .)l .i Mail will respond by typing its version number and date and then listing the messages you have waiting. Then it will type a prompt and await your command. The messages are assigned numbers starting with 1 \*- you refer to the messages with these numbers. .i Mail keeps track of which messages are .i new (have been sent since you last read your mail) and .i read (have been read by you). New messages have an .b N next to them in the header listing and old, but unread messages have a .b U next to them. .i Mail keeps track of new/old and read/unread messages by putting a header field called .q Status into your messages. .pp To look at a specific message, use the .b type command, which may be abbreviated to simply .b t . For example, if you had the following messages: .(l N 1 root Wed Sep 21 09:21 "Tuition fees" N 2 sam Tue Sep 20 22:55 .)l you could examine the first message by giving the command: .(l type 1 .)l which might cause .i Mail to respond with, for example: .(l Message 1: From root Wed Sep 21 09:21:45 1978 Subject: Tuition fees Status: R Tuition fees are due next Wednesday. Don't forget!! .)l Many .i Mail commands that operate on messages take a message number as an argument like the .b type command. For these commands, there is a notion of a current message. When you enter the .i Mail program, the current message is initially the first one. Thus, you can often omit the message number and use, for example, .(l t .)l to type the current message. As a further shorthand, you can type a message by simply giving its message number. Hence, .(l 1 .)l would type the first message. .pp Frequently, it is useful to read the messages in your mailbox in order, one after another. You can read the next message in .i Mail by simply typing a newline. As a special case, you can type a newline as your first command to .i Mail to type the first message. .pp If, after typing a message, you wish to immediately send a reply, you can do so with the .b reply command. .b Reply , like .b type , takes a message number as an argument. .i Mail then begins a message addressed to the user who sent you the message. You may then type in your letter in reply, followed by a <control-d> at the beginning of a line, as before. .i Mail will type EOT, then type the ampersand prompt to indicate its readiness to accept another command. In our example, if, after typing the first message, you wished to reply to it, you might give the command: .(l reply .)l .i Mail responds by typing: .(l To: root Subject: Re: Tuition fees .)l and waiting for you to enter your letter. You are now in the message collection mode described at the beginning of this section and .i Mail will gather up your message up to a control-d. Note that it copies the subject header from the original message. This is useful in that correspondence about a particular matter will tend to retain the same subject heading, making it easy to recognize. If there are other header fields in the message, the information found will also be used. For example, if the letter had a .q "To:" header listing several recipients, .i Mail would arrange to send your replay to the same people as well. Similarly, if the original message contained a .q "Cc:" (carbon copies to) field, .i Mail would send your reply to .i those users, too. .i Mail is careful, though, not too send the message to .i you , even if you appear in the .q "To:" or .q "Cc:" field, unless you ask to be included explicitly. See section 4 for more details. .pp After typing in your letter, the dialog with .i Mail might look like the following: .(l reply To: root Subject: Tuition fees Thanks for the reminder EOT & .)l .pp The .b reply command is especially useful for sustaining extended conversations over the message system, with other .q listening users receiving copies of the conversation. The .b reply command can be abbreviated to .b r . .pp Sometimes you will receive a message that has been sent to several people and wish to reply .i only to the person who sent it. .b Reply with a capital .b R replies to a message, but sends a copy to the sender only. .pp If you wish, while reading your mail, to send a message to someone, but not as a reply to one of your messages, you can send the message directly with the .b mail command, which takes as arguments the names of the recipients you wish to send to. For example, to send a message to .q frank, you would do: .(l mail frank This is to confirm our meeting next Friday at 4. EOT & .)l The .b mail command can be abbreviated to .b m . .pp Normally, each message you receive is saved in the file .i mbox in your login directory at the time you leave .i Mail . Often, however, you will not want to save a particular message you have received because it is only of passing interest. To avoid saving a message in .i mbox you can delete it using the .b delete command. In our example, .(l delete 1 .)l will prevent .i Mail from saving message 1 (from root) in .i mbox . In addition to not saving deleted messages, .i Mail will not let you type them, either. The effect is to make the message disappear altogether, along with its number. The .b delete command can be abbreviated to simply .b d . .pp Many features of .i Mail can be tailored to your liking with the .b set command. The .b set command has two forms, depending on whether you are setting a .i binary option or a .i valued option. Binary options are either on or off. For example, the .q ask option informs .i Mail that each time you send a message, you want it to prompt you for a subject header, to be included in the message. To set the .q ask option, you would type .(l set ask .)l .pp Another useful .i Mail option is .q hold. Unless told otherwise, .i Mail moves the messages from your system mailbox to the file .i mbox in your home directory when you leave .i Mail . If you want .i Mail to keep your letters in the system mailbox instead, you can set the .q hold option. .pp Valued options are values which .i Mail uses to adapt to your tastes. For example, the .q SHELL option tells .i Mail which shell you like to use, and is specified by .(l set SHELL=/bin/csh .)l for example. Note that no spaces are allowed in .q "SHELL=/bin/csh." A complete list of the .i Mail options appears in section 5. .pp Another important valued option is .q crt. If you use a fast video terminal, you will find that when you print long messages, they fly by too quickly for you to read them. With the .q crt option, you can make .i Mail print any message larger than a given number of lines by sending it through a paging program. This program is specified by the valued option PAGER. If PAGER is not set, a default paginator is used. For example, most CRT users with 24-line screens should do: .(l set crt=24 .)l to paginate messages that will not fit on their screens. In the default state, more (default paginator) prints a screenful of information, then types --More--. Type a space to see the next screenful. .pp Another adaptation to user needs that .i Mail provides is that of .i aliases . An alias is simply a name which stands for one or more real user names. .i Mail sent to an alias is really sent to the list of real users associated with it. For example, an alias can be defined for the members of a project, so that you can send mail to the whole project by sending mail to just a single name. The .b alias command in .i Mail defines an alias. Suppose that the users in a project are named Sam, Sally, Steve, and Susan. To define an alias called .q project for them, you would use the .i Mail command: .(l alias project sam sally steve susan .)l The .b alias command can also be used to provide a convenient name for someone whose user name is inconvenient. For example, if a user named .q "Bob Anderson" had the login name .q anderson," you might want to use: .(l alias bob anderson .)l so that you could send mail to the shorter name, .q bob. .pp While the .b alias and .b set commands allow you to customize .i Mail , they have the drawback that they must be retyped each time you enter .i Mail . To make them more convenient to use, .i Mail always looks for two files when it is invoked. It first reads a system wide file .q /etc/mail.rc, then a user specific file, .q .mailrc, which is found in the user's home directory. The system wide file is maintained by the system administrator and contains .b set commands that are applicable to all users of the system. The .q .mailrc file is usually used by each user to set options the way he likes and define individual aliases. For example, my .mailrc file looks like this: .(l set ask nosave SHELL=/bin/csh .)l As you can see, it is possible to set many options in the same .b set command. The .q nosave option is described in section 5. .pp Mail aliasing is implemented at the system-wide level by the mail delivery system .i sendmail . These aliases are stored in the file /usr/lib/aliases and are accessible to all users of the system. The lines in /usr/lib/aliases are of the form: .(l alias: name\*<1\*>, name\*<2\*>, name\*<3\*> .)l where .i alias is the mailing list name and the .i name\*<i\*> are the members of the list. Long lists can be continued onto the next line by starting the next line with a space or tab. Remember that you must execute the shell command .i newaliases after editing /usr/lib/aliases since the delivery system uses an indexed file created by .i newaliases . .pp We have seen that .i Mail can be invoked with command line arguments which are people to send the message to, or with no arguments to read mail. Specifying the .rb -f flag on the command line causes .i Mail to read messages from a file other than your system mailbox. For example, if you have a collection of messages in the file .q letters you can use .i Mail to read them with: .(l % Mail -f letters .)l You can use all the .i Mail commands described in this document to examine, modify, or delete messages from your .q letters file, which will be rewritten when you leave .i Mail with the .b quit command described below. .pp Since mail that you read is saved in the file .i mbox in your home directory by default, you can read .i mbox in your home directory by using simply .(l % Mail -f .)l .pp Normally, messages that you examine using the .b type command are saved in the file .q mbox in your home directory if you leave .i Mail with the .b quit command described below. If you wish to retain a message in your system mailbox you can use the .b preserve command to tell .i Mail to leave it there. The .b preserve command accepts a list of message numbers, just like .b type and may be abbreviated to .b pre . .pp Messages in your system mailbox that you do not examine are normally retained in your system mailbox automatically. If you wish to have such a message saved in .i mbox without reading it, you may use the .b mbox command to have them so saved. For example, .(l mbox 2 .)l in our example would cause the second message (from sam) to be saved in .i mbox when the .b quit command is executed. .b Mbox is also the way to direct messages to your .i mbox file if you have set the .q hold option described above. .b Mbox can be abbreviated to .b mb . .pp When you have perused all the messages of interest, you can leave .i Mail with the .b quit command, which saves the messages you have typed but not deleted in the file .i mbox in your login directory. Deleted messages are discarded irretrievably, and messages left untouched are preserved in your system mailbox so that you will see them the next time you type: .(l % Mail .)l The .b quit command can be abbreviated to simply .b q . .pp If you wish for some reason to leave .i Mail quickly without altering either your system mailbox or .i mbox , you can type the .b x command (short for .b exit ), which will immediately return you to the Shell without changing anything. .pp If, instead, you want to execute a Shell command without leaving .i Mail , you can type the command preceded by an exclamation point, just as in the text editor. Thus, for instance: .(l !date .)l will print the current date without leaving .i Mail . .pp Finally, the .b help command is available to print out a brief summary of the .i Mail commands, using only the single character command abbreviations.