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* Header values which are too long may be truncated. 16 17 If a value of a structured header is longer than 256 (MAXNAME) 18 characters then it may be truncated during output. For example, 19 if a single address in the To: header is longer than 256 characters 20 then it will be truncated which may result in a syntactically 21 invalid address. 22 23* Delivery to programs that generate too much output may cause problems 24 25 If e-mail is delivered to a program which generates too much 26 output, then sendmail may issue an error: 27 28 timeout waiting for input from local during Draining Input 29 30 Make sure that the program does not generate output beyond a 31 status message (corresponding to the exit status). This may 32 require a wrapper around the actual program to redirect output 33 to /dev/null. 34 35 Such a problem has been reported for bulk_mailer. 36 37* Null bytes are not handled properly in headers. 38 39 Sendmail should handle full binary data. As it stands, it handles 40 all values in the body, but not 0x00 in the header. Changing 41 this would require a major restructuring of the code -- for 42 example, almost no C library support could be used to handle 43 strings. 44 45* Header checks are not called if header value is too long or empty. 46 47 If the value of a header is longer than 1250 (MAXNAME + MAXATOM - 6) 48 characters or it contains a single word longer than 256 (MAXNAME) 49 characters then no header check is done even if one is configured for 50 the header. 51 52* Header lines which are too long will be split incorrectly. 53 54 Header lines which are longer than 2045 characters will be split 55 but some characters might be lost. Fix: obey RFC (2)822 and do not 56 send lines that are longer than 1000 characters. 57 58* milter communication fails if a single header is larger than 64K. 59 60 If a single header is larger than 64KB (which is not possible in the 61 default configuration) then it cannot be transferred in one block to 62 libmilter and hence the communication fails. This can be avoided by 63 increasing the constant MILTER_CHUNK_SIZE in 64 include/libmilter/mfdef.h and recompiling sendmail, libmilter, and 65 all (statically linked) milters (or by using an undocumented compile 66 time option: _FFR_MAXDATASIZE; you have to read the source code in 67 order to use this properly). 68 69* Sender addresses whose domain part cause a temporary A record lookup 70 failure but have a valid MX record will be temporarily rejected in 71 the default configuration. Solution: fix the DNS at the sender side. 72 If that's not easy to achieve, possible workarounds are: 73 - add an entry to the access map: 74 dom.ain OK 75 - (only for advanced users) replace 76 77# Resolve map (to check if a host exists in check_mail) 78Kresolve host -a<OKR> -T<TEMP> 79 80 with 81 82# Resolve map (to check if a host exists in check_mail) 83Kcanon host -a<OKR> -T<TEMP> 84Kdnsmx dns -R MX -a<OKR> -T<TEMP> 85Kresolve sequence dnsmx canon 86 87 88* Duplicate error messages. 89 90 Sometimes identical, duplicate error messages can be generated. As 91 near as I can tell, this is rare and relatively innocuous. 92 93* Misleading error messages. 94 95 If an illegal address is specified on the command line together 96 with at least one valid address and PostmasterCopy is set, the 97 DSN does not contain the illegal address, but only the valid 98 address(es). 99 100* \231 considered harmful. 101 102 Header addresses that have the \231 character (and possibly others 103 in the range \201 - \237) behave in odd and usually unexpected ways. 104 105* accept() problem on SVR4. 106 107 Apparently, the sendmail daemon loop (doing accept()s on the network) 108 can get into a weird state on SVR4; it starts logging ``SYSERR: 109 getrequests: accept: Protocol Error''. The workaround is to kill 110 and restart the sendmail daemon. We don't have an SVR4 system at 111 Berkeley that carries more than token mail load, so I can't validate 112 this. It is likely to be a glitch in the sockets emulation, since 113 "Protocol Error" is not possible error code with Berkeley TCP/IP. 114 115 I've also had someone report the message ``sendmail: accept: 116 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 117 not in the sendmail source code, so I assume it is also a bug 118 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 119 on all the systems I have available, including Solaris 2.x.) 120 Apparently, this problem is due to linking -lc before -lsocket; 121 if you are having this problem, check your Makefile. 122 123* accept() problem on Linux. 124 125 The accept() in sendmail daemon loop can return ETIMEDOUT. An 126 error is reported to syslog: 127 128 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 129 getrequests: accept: Connection timed out 130 131 "Connection timed out" is not documented as a valid return from 132 accept(2) and this was believed to be a bug in the Linux kernel. 133 Later information from the Linux kernel group states that Linux 134 2.0 kernels follow RFC1122 while sendmail follows the original BSD 135 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 136 will follow the POSIX draft. 137 138* Excessive mailing list nesting can run out of file descriptors. 139 140 If you have a mailing list that includes lots of other mailing 141 lists, each of which has a separate owner, you can run out of 142 file descriptors. Each mailing list with a separate owner uses 143 one open file descriptor (prior to 8.6.6 it was three open 144 file descriptors per list). This is particularly egregious if 145 you have your connection cache set to be large. 146 147* Connection caching breaks if you pass the port number as an argument. 148 149 If you have a definition such as: 150 151 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 152 M=2100000, T=DNS/RFC822/SMTP, 153 A=IPC [127.0.0.1] $h 154 155 (i.e., where $h is the port number instead of the host name) the 156 connection caching code will break because it won't notice that 157 two messages addressed to different ports should use different 158 connections. 159 160* ESMTP SIZE underestimates the size of a message 161 162 Sendmail makes no allowance for headers that it adds, nor does it 163 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 164 allow for 8->7 bit MIME conversions either. 165 166* Client ignores SIZE parameter. 167 168 When sendmail acts as client and the server specifies a limit 169 for the mail size, sendmail will ignore this and try to send the 170 mail anyway. The server will usually reject the MAIL command 171 which specifies the size of the message and hence this problem 172 is not significant. 173 174* Paths to programs being executed and the mode of program files are 175 not checked. Essentially, the RunProgramInUnsafeDirPath and 176 RunWritableProgram bits in the DontBlameSendmail option are always 177 set. This is not a problem if your system is well managed (that is, 178 if binaries and system directories are mode 755 instead of something 179 foolish like 777). 180 181* 8-bit data in GECOS field 182 183 If the GECOS (personal name) information in the passwd file contains 184 8-bit characters, those characters can be included in the message 185 header, which can cause problems when sending SMTP to hosts that 186 only accept 7-bit characters. 187 188* 8->7 bit MIME conversion 189 190 When sendmail is doing 8->7 bit MIME conversions, and the message 191 contains certain MIME body types that cannot be converted to 7-bit, 192 sendmail will pass the message as 8-bit. 193 194* 7->8 bit MIME conversion 195 196 If a message that is encoded as 7-bit MIME is converted to 8-bit and 197 that message when decoded is illegal (e.g., because of long lines or 198 illegal characters), sendmail can produce an illegal message. 199 200* MIME encoded full name phrases in the From: header 201 202 If a full name phrase includes characters from MustQuoteChars, sendmail 203 will quote the entire full name phrase. If MustQuoteChars includes 204 characters which are not special characters according to STD 11 (RFC 205 822), this quotation can interfere with MIME encoded full name phrases. 206 By default, sendmail includes the single quote character (') in 207 MustQuoteChars even though it is not listed as a special character in 208 STD 11. 209 210* bestmx map with -z flag truncates the list of MX hosts 211 212 A bestmx map configured with the -z flag will truncate the list 213 of MX hosts. This prevents creation of strings which are too 214 long for ruleset parsing. This can have an adverse effect on the 215 relay_based_on_MX feature. 216 217* Saving to ~sender/dead.letter fails if su'ed to root 218 219 If ErrorMode is set to print and an error in sending mail occurs, 220 the normal action is to print a message to the screen and append 221 the message to a dead.letter file in the sender's home directory. 222 In the case where the sender is using su to act as root, the file 223 safety checks prevent sendmail from saving the dead.letter file 224 because the sender's uid and the current real uid do not match. 225 226* Berkeley DB 2.X race condition with fcntl() locking 227 228 There is a race condition for Berkeley DB 2.X databases on 229 operating systems which use fcntl() style locking, such as 230 Solaris. Sendmail locks the map before calling db_open() to 231 prevent others from modifying the map while it is being opened. 232 Unfortunately, Berkeley DB opens the map, closes it, and then 233 reopens it. fcntl() locking drops the lock when any file 234 descriptor pointing to the file is closed, even if it is a 235 different file descriptor than the one used to initially lock 236 the file. As a result there is a possibility that entries in a 237 map might not be found during a map rebuild. As a workaround, 238 you can use makemap to build a map with a new name and then 239 "mv" the new db file to replace the old one. 240 241 Sleepycat Software has added code to avoid this race condition to 242 Berkeley DB versions after 2.7.5. 243 244* File open timeouts not available on hard mounted NFS file systems 245 246 Since SIGALRM does not interrupt an RPC call for hard mounted 247 NFS file systems, it is impossible to implement a timeout on a file 248 open operation. Therefore, while the NFS server is not responding, 249 attempts to open a file on that server will hang. Systems with 250 local mail delivery and NFS hard mounted home directories should be 251 avoided, as attempts to open the forward files could hang. 252 253* Race condition for delivery to set-user-ID files 254 255 Sendmail will deliver to a fail if the file is owned by the DefaultUser 256 or has the set-user-ID bit set. Unfortunately, some systems clear that bit 257 when a file is modified. Sendmail compensates by resetting the file mode 258 back to it's original settings. Unfortunately, there's still a 259 permission failure race as sendmail checks the permissions before locking 260 the file. This is unavoidable as sendmail must verify the file is safe 261 to open before opening it. A file can not be locked until it is open. 262 263* MAIL_HUB always takes precedence over LOCAL_RELAY 264 265 Despite the information in the documentation, MAIL_HUB ($H) will always 266 be used if set instead of LOCAL_RELAY ($R). This will be fixed in a 267 future version. 268 269$Revision: 8.61 $, Last updated $Date: 2011-04-07 17:48:23 $ 270