3 K N O W N B U G S I N S E N D M A I L
6 The following are bugs or deficiencies in sendmail that we are aware of
7 but which have not been fixed in the current release. You probably
8 want to get the most up to date version of this from ftp.sendmail.org
9 in /pub/sendmail/KNOWNBUGS. For descriptions of bugs that have been
10 fixed, see the file RELEASE_NOTES (in the root directory of the sendmail
13 This list is not guaranteed to be complete.
15 * Delivery to programs that generate too much output may cause problems
17 If e-mail is delivered to a program which generates too much
18 output, then sendmail may issue an error:
20 timeout waiting for input from local during Draining Input
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
27 Such a problem has been reported for bulk_mailer.
29 * Null bytes are not handled properly in headers.
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.
37 * Header checks are not called if header value is too long or empty.
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
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:
50 - (only for advanced users) replace
52 # Resolve map (to check if a host exists in check_mail)
53 Kresolve host -a<OKR> -T<TEMP>
57 # Resolve map (to check if a host exists in check_mail)
58 Kcanon host -a<OKR> -T<TEMP>
59 Kdnsmx dns -R MX -a<OKR> -T<TEMP>
60 Kresolve sequence dnsmx canon
63 * Duplicate error messages.
65 Sometimes identical, duplicate error messages can be generated. As
66 near as I can tell, this is rare and relatively innocuous.
68 * Misleading error messages.
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
75 * \231 considered harmful.
77 Header addresses that have the \231 character (and possibly others
78 in the range \201 - \237) behave in odd and usually unexpected ways.
80 * accept() problem on SVR4.
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.
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.
98 * accept() problem on Linux.
100 The accept() in sendmail daemon loop can return ETIMEDOUT. An
101 error is reported to syslog:
103 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root):
104 getrequests: accept: Connection timed out
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.
113 * Excessive mailing list nesting can run out of file descriptors.
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.
122 * Connection caching breaks if you pass the port number as an argument.
124 If you have a definition such as:
126 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21,
127 M=2100000, T=DNS/RFC822/SMTP,
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
135 * ESMTP SIZE underestimates the size of a message
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.
141 * Client ignores SIZE parameter.
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
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
156 * 8-bit data in GECOS field
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.
163 * 8->7 bit MIME conversion
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.
169 * 7->8 bit MIME conversion
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.
175 * MIME encoded full name phrases in the From: header
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
185 * bestmx map with -z flag truncates the list of MX hosts
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.
192 * Saving to ~sender/dead.letter fails if su'ed to root
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.
201 * Berkeley DB 2.X race condition with fcntl() locking
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.
216 Sleepycat Software has added code to avoid this race condition to
217 Berkeley DB versions after 2.7.5.
219 * File open timeouts not available on hard mounted NFS file systems
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.
228 * Race condition for delivery to set-user-ID files
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.
238 * MAIL_HUB always takes precedence over LOCAL_RELAY
240 Despite the information in the documentation, MAIL_HUB ($H) will always
241 be used if set instead of LOCAL_RELAY ($R). This will be fixed in a
244 $Revision: 8.55.2.1 $, Last updated $Date: 2002/12/18 22:38:48 $