sendmail -- Incorrect multipart message handling

Problem Description
A suitably malformed multipart MIME message can cause
sendmail to exceed predefined limits on its stack usage.
Impact
An attacker able to send mail to, or via, a server can cause
queued messages on the system to not be delivered, by causing
the sendmail process which handles queued messages to crash.
Note that this will not stop new messages from entering the
queue (either from local processes, or incoming via SMTP).
Workaround
No workaround is available, but systems which do not receive
email from untrusted sources are not vulnerable.