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 not 0x00 in the header. Changing 33 this would require a major restructuring of the code -- for 34 example, almost no C library support could be used to handle 35 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* Header lines which are too long will be split incorrectly. 45 46 Header lines which are longer than 2045 characters will be split 47 but some characters might be lost. Fix: obey RFC (2)822 and do not 48 send lines that are longer than 1000 characters. 49 50* milter communication fails if a single header is larger than 64K. 51 52 If a single header is larger than 64KB (which is not possible in the 53 default configuration) then it cannot be transferred in one block to 54 libmilter and hence the communication fails. This can be avoided by 55 increasing the constant MILTER_CHUNK_SIZE in 56 include/libmilter/mfdef.h and recompiling sendmail, libmilter, and 57 all (statically linked) milters (or by using an undocumented compile 58 time option: _FFR_MAXDATASIZE; you have to read the source code in 59 order to use this properly). 60 61* Sender addresses whose domain part cause a temporary A record lookup 62 failure but have a valid MX record will be temporarily rejected in 63 the default configuration. Solution: fix the DNS at the sender side. 64 If that's not easy to achieve, possible workarounds are: 65 - add an entry to the access map: 66 dom.ain OK 67 - (only for advanced users) replace 68 69# Resolve map (to check if a host exists in check_mail) 70Kresolve host -a<OKR> -T<TEMP> 71 72 with 73 74# Resolve map (to check if a host exists in check_mail) 75Kcanon host -a<OKR> -T<TEMP> 76Kdnsmx dns -R MX -a<OKR> -T<TEMP> 77Kresolve sequence dnsmx canon 78 79 80* Duplicate error messages. 81 82 Sometimes identical, duplicate error messages can be generated. As 83 near as I can tell, this is rare and relatively innocuous. 84 85* Misleading error messages. 86 87 If an illegal address is specified on the command line together 88 with at least one valid address and PostmasterCopy is set, the 89 DSN does not contain the illegal address, but only the valid 90 address(es). 91 92* \231 considered harmful. 93 94 Header addresses that have the \231 character (and possibly others 95 in the range \201 - \237) behave in odd and usually unexpected ways. 96 97* accept() problem on SVR4. 98 99 Apparently, the sendmail daemon loop (doing accept()s on the network) 100 can get into a weird state on SVR4; it starts logging ``SYSERR: 101 getrequests: accept: Protocol Error''. The workaround is to kill 102 and restart the sendmail daemon. We don't have an SVR4 system at 103 Berkeley that carries more than token mail load, so I can't validate 104 this. It is likely to be a glitch in the sockets emulation, since 105 "Protocol Error" is not possible error code with Berkeley TCP/IP. 106 107 I've also had someone report the message ``sendmail: accept: 108 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 109 not in the sendmail source code, so I assume it is also a bug 110 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 111 on all the systems I have available, including Solaris 2.x.) 112 Apparently, this problem is due to linking -lc before -lsocket; 113 if you are having this problem, check your Makefile. 114 115* accept() problem on Linux. 116 117 The accept() in sendmail daemon loop can return ETIMEDOUT. An 118 error is reported to syslog: 119 120 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 121 getrequests: accept: Connection timed out 122 123 "Connection timed out" is not documented as a valid return from 124 accept(2) and this was believed to be a bug in the Linux kernel. 125 Later information from the Linux kernel group states that Linux 126 2.0 kernels follow RFC1122 while sendmail follows the original BSD 127 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 128 will follow the POSIX draft. 129 130* Excessive mailing list nesting can run out of file descriptors. 131 132 If you have a mailing list that includes lots of other mailing 133 lists, each of which has a separate owner, you can run out of 134 file descriptors. Each mailing list with a separate owner uses 135 one open file descriptor (prior to 8.6.6 it was three open 136 file descriptors per list). This is particularly egregious if 137 you have your connection cache set to be large. 138 139* Connection caching breaks if you pass the port number as an argument. 140 141 If you have a definition such as: 142 143 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 144 M=2100000, T=DNS/RFC822/SMTP, 145 A=IPC [127.0.0.1] $h 146 147 (i.e., where $h is the port number instead of the host name) the 148 connection caching code will break because it won't notice that 149 two messages addressed to different ports should use different 150 connections. 151 152* ESMTP SIZE underestimates the size of a message 153 154 Sendmail makes no allowance for headers that it adds, nor does it 155 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 156 allow for 8->7 bit MIME conversions either. 157 158* Client ignores SIZE parameter. 159 160 When sendmail acts as client and the server specifies a limit 161 for the mail size, sendmail will ignore this and try to send the 162 mail anyway. The server will usually reject the MAIL command 163 which specifies the size of the message and hence this problem 164 is not significant. 165 166* Paths to programs being executed and the mode of program files are 167 not checked. Essentially, the RunProgramInUnsafeDirPath and 168 RunWritableProgram bits in the DontBlameSendmail option are always 169 set. This is not a problem if your system is well managed (that is, 170 if binaries and system directories are mode 755 instead of something 171 foolish like 777). 172 173* 8-bit data in GECOS field 174 175 If the GECOS (personal name) information in the passwd file contains 176 8-bit characters, those characters can be included in the message 177 header, which can cause problems when sending SMTP to hosts that 178 only accept 7-bit characters. 179 180* 8->7 bit MIME conversion 181 182 When sendmail is doing 8->7 bit MIME conversions, and the message 183 contains certain MIME body types that cannot be converted to 7-bit, 184 sendmail will pass the message as 8-bit. 185 186* 7->8 bit MIME conversion 187 188 If a message that is encoded as 7-bit MIME is converted to 8-bit and 189 that message when decoded is illegal (e.g., because of long lines or 190 illegal characters), sendmail can produce an illegal message. 191 192* MIME encoded full name phrases in the From: header 193 194 If a full name phrase includes characters from MustQuoteChars, sendmail 195 will quote the entire full name phrase. If MustQuoteChars includes 196 characters which are not special characters according to STD 11 (RFC 197 822), this quotation can interfere with MIME encoded full name phrases. 198 By default, sendmail includes the single quote character (') in 199 MustQuoteChars even though it is not listed as a special character in 200 STD 11. 201 202* bestmx map with -z flag truncates the list of MX hosts 203 204 A bestmx map configured with the -z flag will truncate the list 205 of MX hosts. This prevents creation of strings which are too 206 long for ruleset parsing. This can have an adverse effect on the 207 relay_based_on_MX feature. 208 209* Saving to ~sender/dead.letter fails if su'ed to root 210 211 If ErrorMode is set to print and an error in sending mail occurs, 212 the normal action is to print a message to the screen and append 213 the message to a dead.letter file in the sender's home directory. 214 In the case where the sender is using su to act as root, the file 215 safety checks prevent sendmail from saving the dead.letter file 216 because the sender's uid and the current real uid do not match. 217 218* Berkeley DB 2.X race condition with fcntl() locking 219 220 There is a race condition for Berkeley DB 2.X databases on 221 operating systems which use fcntl() style locking, such as 222 Solaris. Sendmail locks the map before calling db_open() to 223 prevent others from modifying the map while it is being opened. 224 Unfortunately, Berkeley DB opens the map, closes it, and then 225 reopens it. fcntl() locking drops the lock when any file 226 descriptor pointing to the file is closed, even if it is a 227 different file descriptor than the one used to initially lock 228 the file. As a result there is a possibility that entries in a 229 map might not be found during a map rebuild. As a workaround, 230 you can use makemap to build a map with a new name and then 231 "mv" the new db file to replace the old one. 232 233 Sleepycat Software has added code to avoid this race condition to 234 Berkeley DB versions after 2.7.5. 235 236* File open timeouts not available on hard mounted NFS file systems 237 238 Since SIGALRM does not interrupt an RPC call for hard mounted 239 NFS file systems, it is impossible to implement a timeout on a file 240 open operation. Therefore, while the NFS server is not responding, 241 attempts to open a file on that server will hang. Systems with 242 local mail delivery and NFS hard mounted home directories should be 243 avoided, as attempts to open the forward files could hang. 244 245* Race condition for delivery to set-user-ID files 246 247 Sendmail will deliver to a fail if the file is owned by the DefaultUser 248 or has the set-user-ID bit set. Unfortunately, some systems clear that bit 249 when a file is modified. Sendmail compensates by resetting the file mode 250 back to it's original settings. Unfortunately, there's still a 251 permission failure race as sendmail checks the permissions before locking 252 the file. This is unavoidable as sendmail must verify the file is safe 253 to open before opening it. A file can not be locked until it is open. 254 255* MAIL_HUB always takes precedence over LOCAL_RELAY 256 257 Despite the information in the documentation, MAIL_HUB ($H) will always 258 be used if set instead of LOCAL_RELAY ($R). This will be fixed in a 259 future version. 260 261$Revision: 8.60 $, Last updated $Date: 2007/12/04 01:16:50 $ 262