1 2 3 K N O W N B U G S I N S E N D M A I L 4 5 6The following are bugs or deficiencies in sendmail that we are aware of 7but which have not been fixed in the current release. You probably 8want to get the most up to date version of this from ftp.sendmail.org 9in /pub/sendmail/KNOWNBUGS. For descriptions of bugs that have been 10fixed, see the file RELEASE_NOTES (in the root directory of the sendmail 11distribution). 12 13This list is not guaranteed to be complete. 14 15* Delivery to programs that generate too much output may cause problems 16 17 If e-mail is delivered to a program which generates too much 18 output, then sendmail may issue an error: 19 20 timeout waiting for input from local during Draining Input 21 22 Make sure that the program does not generate output beyond a 23 status message (corresponding to the exit status). This may 24 require a wrapper around the actual program to redirect output 25 to /dev/null. 26 27 Such a problem has been reported for bulk_mailer. 28 29* Null bytes are not handled properly in headers. 30 31 Sendmail should handle full binary data. As it stands, it handles 32 all values in the body, but only 0x01-0x80 and 0xA0-0xFF in 33 the header. Notably missing is 0x00, which would require a major 34 restructuring of the code -- for example, almost no C library support 35 could be used to handle strings. 36 37* Header checks are not called if header value is too long or empty. 38 39 If the value of a header is longer than 1250 (MAXNAME + MAXATOM - 6) 40 characters or it contains a single word longer than 256 (MAXNAME) 41 characters then no header check is done even if one is configured for 42 the header. 43 44* Sender addresses whose domain part cause a temporary A record lookup 45 failure but have a valid MX record will be temporarily rejected in 46 the default configuration. Solution: fix the DNS at the sender side. 47 If that's not easy to achieve, possible workarounds are: 48 - add an entry to the access map: 49 dom.ain OK 50 - (only for advanced users) replace 51 52# Resolve map (to check if a host exists in check_mail) 53Kresolve host -a<OKR> -T<TEMP> 54 55 with 56 57# Resolve map (to check if a host exists in check_mail) 58Kcanon host -a<OKR> -T<TEMP> 59Kdnsmx dns -R MX -a<OKR> -T<TEMP> 60Kresolve sequence dnsmx canon 61 62 63* Duplicate error messages. 64 65 Sometimes identical, duplicate error messages can be generated. As 66 near as I can tell, this is rare and relatively innocuous. 67 68* Misleading error messages. 69 70 If an illegal address is specified on the command line together 71 with at least one valid address and PostmasterCopy is set, the 72 DSN does not contain the illegal address, but only the valid 73 address(es). 74 75* \231 considered harmful. 76 77 Header addresses that have the \231 character (and possibly others 78 in the range \201 - \237) behave in odd and usually unexpected ways. 79 80* accept() problem on SVR4. 81 82 Apparently, the sendmail daemon loop (doing accept()s on the network) 83 can get into a weird state on SVR4; it starts logging ``SYSERR: 84 getrequests: accept: Protocol Error''. The workaround is to kill 85 and restart the sendmail daemon. We don't have an SVR4 system at 86 Berkeley that carries more than token mail load, so I can't validate 87 this. It is likely to be a glitch in the sockets emulation, since 88 "Protocol Error" is not possible error code with Berkeley TCP/IP. 89 90 I've also had someone report the message ``sendmail: accept: 91 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 92 not in the sendmail source code, so I assume it is also a bug 93 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 94 on all the systems I have available, including Solaris 2.x.) 95 Apparently, this problem is due to linking -lc before -lsocket; 96 if you are having this problem, check your Makefile. 97 98* accept() problem on Linux. 99 100 The accept() in sendmail daemon loop can return ETIMEDOUT. An 101 error is reported to syslog: 102 103 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 104 getrequests: accept: Connection timed out 105 106 "Connection timed out" is not documented as a valid return from 107 accept(2) and this was believed to be a bug in the Linux kernel. 108 Later information from the Linux kernel group states that Linux 109 2.0 kernels follow RFC1122 while sendmail follows the original BSD 110 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 111 will follow the POSIX draft. 112 113* Excessive mailing list nesting can run out of file descriptors. 114 115 If you have a mailing list that includes lots of other mailing 116 lists, each of which has a separate owner, you can run out of 117 file descriptors. Each mailing list with a separate owner uses 118 one open file descriptor (prior to 8.6.6 it was three open 119 file descriptors per list). This is particularly egregious if 120 you have your connection cache set to be large. 121 122* Connection caching breaks if you pass the port number as an argument. 123 124 If you have a definition such as: 125 126 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 127 M=2100000, T=DNS/RFC822/SMTP, 128 A=IPC [127.0.0.1] $h 129 130 (i.e., where $h is the port number instead of the host name) the 131 connection caching code will break because it won't notice that 132 two messages addressed to different ports should use different 133 connections. 134 135* ESMTP SIZE underestimates the size of a message 136 137 Sendmail makes no allowance for headers that it adds, nor does it 138 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 139 allow for 8->7 bit MIME conversions either. 140 141* Client ignores SIZE parameter. 142 143 When sendmail acts as client and the server specifies a limit 144 for the mail size, sendmail will ignore this and try to send the 145 mail anyway. The server will usually reject the MAIL command 146 which specifies the size of the message and hence this problem 147 is not significant. 148 149* Paths to programs being executed and the mode of program files are 150 not checked. Essentially, the RunProgramInUnsafeDirPath and 151 RunWritableProgram bits in the DontBlameSendmail option are always 152 set. This is not a problem if your system is well managed (that is, 153 if binaries and system directories are mode 755 instead of something 154 foolish like 777). 155 156* 8-bit data in GECOS field 157 158 If the GECOS (personal name) information in the passwd file contains 159 8-bit characters, those characters can be included in the message 160 header, which can cause problems when sending SMTP to hosts that 161 only accept 7-bit characters. 162 163* 8->7 bit MIME conversion 164 165 When sendmail is doing 8->7 bit MIME conversions, and the message 166 contains certain MIME body types that cannot be converted to 7-bit, 167 sendmail will strip the message to 7-bit. 168 169* 7->8 bit MIME conversion 170 171 If a message that is encoded as 7-bit MIME is converted to 8-bit and 172 that message when decoded is illegal (e.g., because of long lines or 173 illegal characters), sendmail can produce an illegal message. 174 175* MIME encoded full name phrases in the From: header 176 177 If a full name phrase includes characters from MustQuoteChars, sendmail 178 will quote the entire full name phrase. If MustQuoteChars includes 179 characters which are not special characters according to STD 11 (RFC 180 822), this quotation can interfere with MIME encoded full name phrases. 181 By default, sendmail includes the single quote character (') in 182 MustQuoteChars even though it is not listed as a special character in 183 STD 11. 184 185* bestmx map with -z flag truncates the list of MX hosts 186 187 A bestmx map configured with the -z flag will truncate the list 188 of MX hosts. This prevents creation of strings which are too 189 long for ruleset parsing. This can have an adverse effect on the 190 relay_based_on_MX feature. 191 192* Saving to ~sender/dead.letter fails if su'ed to root 193 194 If ErrorMode is set to print and an error in sending mail occurs, 195 the normal action is to print a message to the screen and append 196 the message to a dead.letter file in the sender's home directory. 197 In the case where the sender is using su to act as root, the file 198 safety checks prevent sendmail from saving the dead.letter file 199 because the sender's uid and the current real uid do not match. 200 201* Berkeley DB 2.X race condition with fcntl() locking 202 203 There is a race condition for Berkeley DB 2.X databases on 204 operating systems which use fcntl() style locking, such as 205 Solaris. Sendmail locks the map before calling db_open() to 206 prevent others from modifying the map while it is being opened. 207 Unfortunately, Berkeley DB opens the map, closes it, and then 208 reopens it. fcntl() locking drops the lock when any file 209 descriptor pointing to the file is closed, even if it is a 210 different file descriptor than the one used to initially lock 211 the file. As a result there is a possibility that entries in a 212 map might not be found during a map rebuild. As a workaround, 213 you can use makemap to build a map with a new name and then 214 "mv" the new db file to replace the old one. 215 216 Sleepycat Software has added code to avoid this race condition to 217 Berkeley DB versions after 2.7.5. 218 219* File open timeouts not available on hard mounted NFS file systems 220 221 Since SIGALRM does not interrupt an RPC call for hard mounted 222 NFS file systems, it is impossible to implement a timeout on a file 223 open operation. Therefore, while the NFS server is not responding, 224 attempts to open a file on that server will hang. Systems with 225 local mail delivery and NFS hard mounted home directories should be 226 avoided, as attempts to open the forward files could hang. 227 228* Race condition for delivery to set-user-ID files 229 230 Sendmail will deliver to a fail if the file is owned by the DefaultUser 231 or has the set-user-ID bit set. Unfortunately, some systems clear that bit 232 when a file is modified. Sendmail compensates by resetting the file mode 233 back to it's original settings. Unfortunately, there's still a 234 permission failure race as sendmail checks the permissions before locking 235 the file. This is unavoidable as sendmail must verify the file is safe 236 to open before opening it. A file can not be locked until it is open. 237 238$Revision: 8.55 $, Last updated $Date: 2002/03/05 00:45:54 $ 239