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* Berkeley DB map locking problem with fcntl(). 24 25 For Linux the default is to use fcntl() for file locking. However, 26 this does not work with Berkeley DB 5.x and probably later. 27 Switching to flock(), i.e., compile with -DHASFLOCK fixes this 28 (however, there have been problems with flock() on some Linux 29 versions). Alternatively, use CDB or an earlier BDB version. 30 31* Delivery to programs that generate too much output may cause problems 32 33 If e-mail is delivered to a program which generates too much 34 output, then sendmail may issue an error: 35 36 timeout waiting for input from local during Draining Input 37 38 Make sure that the program does not generate output beyond a 39 status message (corresponding to the exit status). This may 40 require a wrapper around the actual program to redirect output 41 to /dev/null. 42 43 Such a problem has been reported for bulk_mailer. 44 45* Null bytes are not handled properly in headers. 46 47 Sendmail should handle full binary data. As it stands, it handles 48 all values in the body, but not 0x00 in the header. Changing 49 this would require a major restructuring of the code -- for 50 example, almost no C library support could be used to handle 51 strings. 52 53* Header checks are not called if header value is too long or empty. 54 55 If the value of a header is longer than 1250 (MAXNAME + MAXATOM - 6) 56 characters or it contains a single word longer than 256 (MAXNAME) 57 characters then no header check is done even if one is configured for 58 the header. 59 60* Header lines which are too long will be split incorrectly. 61 62 Header lines which are longer than 2045 characters will be split 63 but some characters might be lost. Fix: obey RFC (2)822 and do not 64 send lines that are longer than 1000 characters. 65 66* milter communication fails if a single header is larger than 64K. 67 68 If a single header is larger than 64KB (which is not possible in the 69 default configuration) then it cannot be transferred in one block to 70 libmilter and hence the communication fails. This can be avoided by 71 increasing the constant MILTER_CHUNK_SIZE in 72 include/libmilter/mfdef.h and recompiling sendmail, libmilter, and 73 all (statically linked) milters (or by using undocumented compile 74 time options: _FFR_MAXDATASIZE/_FFR_MDS_NEGOTIATE; you have to 75 read the source code in order to use these properly). 76 77* Sender addresses whose domain part cause a temporary A record lookup 78 failure but have a valid MX record will be temporarily rejected in 79 the default configuration. Solution: fix the DNS at the sender side. 80 If that's not easy to achieve, possible workarounds are: 81 - add an entry to the access map: 82 dom.ain OK 83 - (only for advanced users) replace 84 85# Resolve map (to check if a host exists in check_mail) 86Kresolve host -a<OKR> -T<TEMP> 87 88 with 89 90# Resolve map (to check if a host exists in check_mail) 91Kcanon host -a<OKR> -T<TEMP> 92Kdnsmx dns -R MX -a<OKR> -T<TEMP> 93Kresolve sequence dnsmx canon 94 95 96* Duplicate error messages. 97 98 Sometimes identical, duplicate error messages can be generated. As 99 near as I can tell, this is rare and relatively innocuous. 100 101* Misleading error messages. 102 103 If an illegal address is specified on the command line together 104 with at least one valid address and PostmasterCopy is set, the 105 DSN does not contain the illegal address, but only the valid 106 address(es). 107 108* AuthRealm for Cyrus SASL may not work as expected. The man page 109 and the actual usage for sasl_server_new() seem to differ. 110 Feedback for the "correct" usage is welcome, a patch to match 111 the description of the man page is in contrib/AuthRealm.p0. 112 113* accept() problem on SVR4. 114 115 Apparently, the sendmail daemon loop (doing accept()s on the network) 116 can get into a weird state on SVR4; it starts logging ``SYSERR: 117 getrequests: accept: Protocol Error''. The workaround is to kill 118 and restart the sendmail daemon. We don't have an SVR4 system at 119 Berkeley that carries more than token mail load, so I can't validate 120 this. It is likely to be a glitch in the sockets emulation, since 121 "Protocol Error" is not possible error code with Berkeley TCP/IP. 122 123 I've also had someone report the message ``sendmail: accept: 124 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 125 not in the sendmail source code, so I assume it is also a bug 126 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 127 on all the systems I have available, including Solaris 2.x.) 128 Apparently, this problem is due to linking -lc before -lsocket; 129 if you are having this problem, check your Makefile. 130 131* accept() problem on Linux. 132 133 The accept() in sendmail daemon loop can return ETIMEDOUT. An 134 error is reported to syslog: 135 136 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 137 getrequests: accept: Connection timed out 138 139 "Connection timed out" is not documented as a valid return from 140 accept(2) and this was believed to be a bug in the Linux kernel. 141 Later information from the Linux kernel group states that Linux 142 2.0 kernels follow RFC1122 while sendmail follows the original BSD 143 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 144 will follow the POSIX draft. 145 146* Excessive mailing list nesting can run out of file descriptors. 147 148 If you have a mailing list that includes lots of other mailing 149 lists, each of which has a separate owner, you can run out of 150 file descriptors. Each mailing list with a separate owner uses 151 one open file descriptor (prior to 8.6.6 it was three open 152 file descriptors per list). This is particularly egregious if 153 you have your connection cache set to be large. 154 155* Connection caching breaks if you pass the port number as an argument. 156 157 If you have a definition such as: 158 159 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 160 M=2100000, T=DNS/RFC822/SMTP, 161 A=IPC [127.0.0.1] $h 162 163 (i.e., where $h is the port number instead of the host name) the 164 connection caching code will break because it won't notice that 165 two messages addressed to different ports should use different 166 connections. 167 168* ESMTP SIZE underestimates the size of a message 169 170 Sendmail makes no allowance for headers that it adds, nor does it 171 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 172 allow for 8->7 bit MIME conversions either. 173 174* Client ignores SIZE parameter. 175 176 When sendmail acts as client and the server specifies a limit for 177 the mail size, sendmail will ignore this and try to send the mail 178 anyway (unless _FFR_CLIENT_SIZE is used). The server will usually 179 reject the MAIL command which specifies the size of the message 180 and hence this problem is not significant. 181 182* Paths to programs being executed and the mode of program files are 183 not checked. Essentially, the RunProgramInUnsafeDirPath and 184 RunWritableProgram bits in the DontBlameSendmail option are always 185 set. This is not a problem if your system is well managed (that is, 186 if binaries and system directories are mode 755 instead of something 187 foolish like 777). 188 189* 8-bit data in GECOS field 190 191 If the GECOS (personal name) information in the passwd file contains 192 8-bit characters, those characters can be included in the message 193 header, which can cause problems when sending SMTP to hosts that 194 only accept 7-bit characters. 195 196* 8->7 bit MIME conversion 197 198 When sendmail is doing 8->7 bit MIME conversions, and the message 199 contains certain MIME body types that cannot be converted to 7-bit, 200 sendmail will pass the message as 8-bit. 201 202* 7->8 bit MIME conversion 203 204 If a message that is encoded as 7-bit MIME is converted to 8-bit and 205 that message when decoded is illegal (e.g., because of long lines or 206 illegal characters), sendmail can produce an illegal message. 207 208* MIME encoded full name phrases in the From: header 209 210 If a full name phrase includes characters from MustQuoteChars, sendmail 211 will quote the entire full name phrase. If MustQuoteChars includes 212 characters which are not special characters according to STD 11 (RFC 213 822), this quotation can interfere with MIME encoded full name phrases. 214 By default, sendmail includes the single quote character (') in 215 MustQuoteChars even though it is not listed as a special character in 216 STD 11. 217 218* bestmx map with -z flag truncates the list of MX hosts 219 220 A bestmx map configured with the -z flag will truncate the list 221 of MX hosts. This prevents creation of strings which are too 222 long for ruleset parsing. This can have an adverse effect on the 223 relay_based_on_MX feature. 224 225* Saving to ~sender/dead.letter fails if su'ed to root 226 227 If ErrorMode is set to print and an error in sending mail occurs, 228 the normal action is to print a message to the screen and append 229 the message to a dead.letter file in the sender's home directory. 230 In the case where the sender is using su to act as root, the file 231 safety checks prevent sendmail from saving the dead.letter file 232 because the sender's uid and the current real uid do not match. 233 234* Berkeley DB 2.X race condition with fcntl() locking 235 236 There is a race condition for Berkeley DB 2.X databases on 237 operating systems which use fcntl() style locking, such as 238 Solaris. Sendmail locks the map before calling db_open() to 239 prevent others from modifying the map while it is being opened. 240 Unfortunately, Berkeley DB opens the map, closes it, and then 241 reopens it. fcntl() locking drops the lock when any file 242 descriptor pointing to the file is closed, even if it is a 243 different file descriptor than the one used to initially lock 244 the file. As a result there is a possibility that entries in a 245 map might not be found during a map rebuild. As a workaround, 246 you can use makemap to build a map with a new name and then 247 "mv" the new db file to replace the old one. 248 249 Sleepycat Software has added code to avoid this race condition to 250 Berkeley DB versions after 2.7.5. 251 252* File open timeouts not available on hard mounted NFS file systems 253 254 Since SIGALRM does not interrupt an RPC call for hard mounted 255 NFS file systems, it is impossible to implement a timeout on a file 256 open operation. Therefore, while the NFS server is not responding, 257 attempts to open a file on that server will hang. Systems with 258 local mail delivery and NFS hard mounted home directories should be 259 avoided, as attempts to open the forward files could hang. 260 261* Race condition for delivery to set-user-ID files 262 263 Sendmail will deliver to a file if the file is owned by the DefaultUser 264 or has the set-user-ID bit set. Unfortunately, some systems clear that bit 265 when a file is modified. Sendmail compensates by resetting the file mode 266 back to it's original settings. Unfortunately, there's still a 267 permission failure race as sendmail checks the permissions before locking 268 the file. This is unavoidable as sendmail must verify the file is safe 269 to open before opening it. A file can not be locked until it is open. 270 271* MAIL_HUB always takes precedence over LOCAL_RELAY 272 273 Despite the information in the documentation, MAIL_HUB ($H) will always 274 be used if set instead of LOCAL_RELAY ($R). This will be fixed in a 275 future version. 276 277