Short timeouts could cause fetchmail to not wait long enough for the
"250 Ok" after shipping a long message, particularly with synchronous
mailers and extensive spam filtering. This caused fetchmail to re-fetch
long messages.

While the actual fix is making sure that the timeout is no shorter than
the time the SMTP server takes to process the message, we now enforce
the minimum RFC-5321 recommended timeouts even if the user configures a
lower timeout.

This is to fix Berlios Bug #10972, reported by Viktor Binzberger.

NOTE: it is untested whether we will properly delete the message from
the POP3/IMAP server or mark it as seen, as the upstream server may
close the connection sooner.

svn path=/branches/BRANCH_6-3/; revision=5338