multiple IMAP sessions when connecting from one client

[Jochen Bern]

On -10.01.-28163 20:59, Martin Vegter wrote:
> I have noticed that every time I connect with Thunderbird to my
> server via IMAP, not one but 4 connections are being logged [...]
> Is this normal behavior?

>From the point of view of dovecot, as a *server* implementation, it is
pretty normal to answer as many IMAP connections as a legitimate client
sees fit to start. After all, the IMAP protocol is *designed* to allow
multiple concurrent connections for the same user/mailbox even from
*different* clients (and NATed clients exist).

Note, however, that dovecot has various limits set and active by
default, the most relevant for this matter probably being a
mail_max_userip_connections of 10.

>From the client's perspective, there may be good reasons to have several
connections at once (in particular, ability to run several operations in
parallel), and then there obviously are less convincing ones as well
(I've seen appliances checking for new mail every couple minutes,
connecting for less than 1s, but opening *TWO* connections to do so).

Regards,
								J. Bern
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