IMAP on 993/SSL or 143/STARTTLS?

Jochen Bern Jochen.Bern at LINworks.de
Mon Aug 18 17:39:27 UTC 2014


On -10.01.-28163 20:59, Alex wrote:
> Why would someone choose one over the other?

There's no *global* reason to choose one over the other AFAIK, but I've
seen individual projects find reasons ruling out the STARTTLS approach.
Most of them were variations of "we want SSL and $INTERIOR_PROTOCOL
provided by different, non-integrated solutions" - from crypto-enabling
a legacy system (just slap socat/stunnel/whatever in front of it to
provide the SSL) to inserting a content scanner of your choice to
hardware crypto accelerators that literally aren't built to provide the
SSL-wrapped service.

Then there's the occasional client that needs to be installed someplace
where the network admins, CSO, company policy, ... just say "no" to
connections that *possibly could* wind up being unencrypted.

I'm not aware of a case where STARTTLS was OK but native SSL got
*firmly* ruled out (though I *do* know some organizations who pay their
firewalling providers heftily per year *and rule*).

> Can I ask the same question about SMTP and submission?

For areas where you control (directly, or per mutual agreement) both
servers and clients, the situation's the same as for IMAP.

For MTAs exchanging e-mails with anywhere in the Internet the DNS points
them to, anything not available via port 25 plain doesn't (yet?) exist,
of course.

And then there's the occasional enabled-by-default Cisco SMTP Fixup
getting in the way of STARTTLS ... :-C

Regards,
								J. Bern
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