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, the 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* \231 considered harmful. 109 110 Header addresses that have the \231 character (and possibly others 111 in the range \201 - \237) behave in odd and usually unexpected ways. 112 113* AuthRealm for Cyrus SASL may not work as expected. The man page 114 and the actual usage for sasl_server_new() seem to differ. 115 Feedback for the "correct" usage is welcome, a patch to match 116 the description of the man page is in contrib/AuthRealm.p0. 117 118* accept() problem on SVR4. 119 120 Apparently, the sendmail daemon loop (doing accept()s on the network) 121 can get into a weird state on SVR4; it starts logging ``SYSERR: 122 getrequests: accept: Protocol Error''. The workaround is to kill 123 and restart the sendmail daemon. We don't have an SVR4 system at 124 Berkeley that carries more than token mail load, so I can't validate 125 this. It is likely to be a glitch in the sockets emulation, since 126 "Protocol Error" is not possible error code with Berkeley TCP/IP. 127 128 I've also had someone report the message ``sendmail: accept: 129 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 130 not in the sendmail source code, so I assume it is also a bug 131 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 132 on all the systems I have available, including Solaris 2.x.) 133 Apparently, this problem is due to linking -lc before -lsocket; 134 if you are having this problem, check your Makefile. 135 136* accept() problem on Linux. 137 138 The accept() in sendmail daemon loop can return ETIMEDOUT. An 139 error is reported to syslog: 140 141 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 142 getrequests: accept: Connection timed out 143 144 "Connection timed out" is not documented as a valid return from 145 accept(2) and this was believed to be a bug in the Linux kernel. 146 Later information from the Linux kernel group states that Linux 147 2.0 kernels follow RFC1122 while sendmail follows the original BSD 148 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 149 will follow the POSIX draft. 150 151* Excessive mailing list nesting can run out of file descriptors. 152 153 If you have a mailing list that includes lots of other mailing 154 lists, each of which has a separate owner, you can run out of 155 file descriptors. Each mailing list with a separate owner uses 156 one open file descriptor (prior to 8.6.6 it was three open 157 file descriptors per list). This is particularly egregious if 158 you have your connection cache set to be large. 159 160* Connection caching breaks if you pass the port number as an argument. 161 162 If you have a definition such as: 163 164 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 165 M=2100000, T=DNS/RFC822/SMTP, 166 A=IPC [127.0.0.1] $h 167 168 (i.e., where $h is the port number instead of the host name) the 169 connection caching code will break because it won't notice that 170 two messages addressed to different ports should use different 171 connections. 172 173* ESMTP SIZE underestimates the size of a message 174 175 Sendmail makes no allowance for headers that it adds, nor does it 176 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 177 allow for 8->7 bit MIME conversions either. 178 179* Client ignores SIZE parameter. 180 181 When sendmail acts as client and the server specifies a limit 182 for the mail size, sendmail will ignore this and try to send the 183 mail anyway. The server will usually reject the MAIL command 184 which specifies the size of the message and hence this problem 185 is not significant. 186 187* Paths to programs being executed and the mode of program files are 188 not checked. Essentially, the RunProgramInUnsafeDirPath and 189 RunWritableProgram bits in the DontBlameSendmail option are always 190 set. This is not a problem if your system is well managed (that is, 191 if binaries and system directories are mode 755 instead of something 192 foolish like 777). 193 194* 8-bit data in GECOS field 195 196 If the GECOS (personal name) information in the passwd file contains 197 8-bit characters, those characters can be included in the message 198 header, which can cause problems when sending SMTP to hosts that 199 only accept 7-bit characters. 200 201* 8->7 bit MIME conversion 202 203 When sendmail is doing 8->7 bit MIME conversions, and the message 204 contains certain MIME body types that cannot be converted to 7-bit, 205 sendmail will pass the message as 8-bit. 206 207* 7->8 bit MIME conversion 208 209 If a message that is encoded as 7-bit MIME is converted to 8-bit and 210 that message when decoded is illegal (e.g., because of long lines or 211 illegal characters), sendmail can produce an illegal message. 212 213* MIME encoded full name phrases in the From: header 214 215 If a full name phrase includes characters from MustQuoteChars, sendmail 216 will quote the entire full name phrase. If MustQuoteChars includes 217 characters which are not special characters according to STD 11 (RFC 218 822), this quotation can interfere with MIME encoded full name phrases. 219 By default, sendmail includes the single quote character (') in 220 MustQuoteChars even though it is not listed as a special character in 221 STD 11. 222 223* bestmx map with -z flag truncates the list of MX hosts 224 225 A bestmx map configured with the -z flag will truncate the list 226 of MX hosts. This prevents creation of strings which are too 227 long for ruleset parsing. This can have an adverse effect on the 228 relay_based_on_MX feature. 229 230* Saving to ~sender/dead.letter fails if su'ed to root 231 232 If ErrorMode is set to print and an error in sending mail occurs, 233 the normal action is to print a message to the screen and append 234 the message to a dead.letter file in the sender's home directory. 235 In the case where the sender is using su to act as root, the file 236 safety checks prevent sendmail from saving the dead.letter file 237 because the sender's uid and the current real uid do not match. 238 239* Berkeley DB 2.X race condition with fcntl() locking 240 241 There is a race condition for Berkeley DB 2.X databases on 242 operating systems which use fcntl() style locking, such as 243 Solaris. Sendmail locks the map before calling db_open() to 244 prevent others from modifying the map while it is being opened. 245 Unfortunately, Berkeley DB opens the map, closes it, and then 246 reopens it. fcntl() locking drops the lock when any file 247 descriptor pointing to the file is closed, even if it is a 248 different file descriptor than the one used to initially lock 249 the file. As a result there is a possibility that entries in a 250 map might not be found during a map rebuild. As a workaround, 251 you can use makemap to build a map with a new name and then 252 "mv" the new db file to replace the old one. 253 254 Sleepycat Software has added code to avoid this race condition to 255 Berkeley DB versions after 2.7.5. 256 257* File open timeouts not available on hard mounted NFS file systems 258 259 Since SIGALRM does not interrupt an RPC call for hard mounted 260 NFS file systems, it is impossible to implement a timeout on a file 261 open operation. Therefore, while the NFS server is not responding, 262 attempts to open a file on that server will hang. Systems with 263 local mail delivery and NFS hard mounted home directories should be 264 avoided, as attempts to open the forward files could hang. 265 266* Race condition for delivery to set-user-ID files 267 268 Sendmail will deliver to a file if the file is owned by the DefaultUser 269 or has the set-user-ID bit set. Unfortunately, some systems clear that bit 270 when a file is modified. Sendmail compensates by resetting the file mode 271 back to it's original settings. Unfortunately, there's still a 272 permission failure race as sendmail checks the permissions before locking 273 the file. This is unavoidable as sendmail must verify the file is safe 274 to open before opening it. A file can not be locked until it is open. 275 276* MAIL_HUB always takes precedence over LOCAL_RELAY 277 278 Despite the information in the documentation, MAIL_HUB ($H) will always 279 be used if set instead of LOCAL_RELAY ($R). This will be fixed in a 280 future version. 281 282