K N O W N  B U G S 

I N  S E N D M A I L (for 8.8.6)

The following are bugs or deficiencies in sendmail that I am aware of but which have not been fixed in the current release. You probably want to get the most up to date version of this from ftp.sendmail.org in /pub/sendmail/KNOWNBUGS.
For descriptions of bugs that have been fixed, see the file RELEASE_NOTES (in the root directory of the sendmail distribution). This list is not guaranteed to be complete.

• Null bytes are not handled properly in headers. Sendmail should handle full binary data. As it stands, it handles all values in the body, but only 0x01-0x80 and 0xA0-0xFF in the header. Notably missing is 0x00, which would require a major restructuring of the code -- for example, almost no C library support could be used to handle strings.
• Duplicate error messages. Sometimes identical, duplicate error messages can be generated. As near as I can tell, this is rare and relatively innocuous.
• $c (hop count) macro improperly set. The $c macro is supposed to contain the current hop count, for use when calling a mailer. This macro is initialized too early, and is always zero (or the value of the -c command line flag, if any). This macro will probably be removed entirely in a future release; I don't believe there are any mailers left that require it.
• If you EXPN a list or user that has a program mailer, the output of EXPN will include ``@local.host.name''. You can't actually mail to this address. It's not clear what the right behaviour is in this circumstance.
• \231 considered harmful. Header addresses that have the \231 character (and possibly others in the range \201 - \237) behave in odd and usually unexpected ways.
• accept() problem on SVR4. Apparently, the sendmail daemon loop (doing accept()s on the network) can get into a wierd state on SVR4; it starts logging ``SYSERR: getrequests: accept: Protocol Error''. The workaround is to kill and restart the sendmail daemon. We don't have an SVR4 system at Berkeley that carries more than token mail load, so I can't validate this. It is likely to be a glitch in the sockets emulation, since "Protocol Error" is not possible error code with Berkeley TCP/IP. I've also had someone report the message ``sendmail: accept: SIOCGPGRP failed errno 22'' on an SVR4 system. This message is not in the sendmail source code, so I assume it is also a bug in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" on all the systems I have available, including Solaris 2.x.) Apparently, this problem is due to linking -lc before -lsocket; if you are having this problem, check your Makefile.
• accept() problem on Linux. Apparently, the accept() in sendmail daemon loop can return ETIMEDOUT and cause sendmail to sleep for 5 seconds during which time no new connections will be accepted. An error is reported to syslog: Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): getrequests: accept: Connection timed out "Connection timed out" is not documented as a valid return from accept(2) and this is believed to be a bug in the Linux kernel.
• Excessive mailing list nesting can run out of file descriptors. If you have a mailing list that includes lots of other mailing lists, each of which has a separate owner, you can run out of file descriptors. Each mailing list with a separate owner uses one open file descriptor (prior to 8.6.6 it was three open file descriptors per list). This is particularly egregious if you have your connection cache set to be large.
• Connection caching breaks if you pass the port number as an argument. If you have a definition such as: Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, M=2100000, T=DNS/RFC822/SMTP, A=IPC [127.0.0.1] $h (i.e., where $h is the port number instead of the host name) the connection caching code will break because it won't notice that two messages addressed to different ports should use different connections.
• ESMTP SIZE underestimates the size of a message Sendmail makes no allowance for headers that it adds, nor does it account for the SMTP on-the-wire \r\n expansion. It probably doesn't allow for 8->7 bit MIME conversions either. (Version 8.25, last updated 6/13/97)