[Dovecot] Testing IMAP clients with Dovecot, problems with MacMail

Troy Engel tengel at fluid.com
Fri May 4 00:41:14 EEST 2007

Stewart Dean wrote:
>> It looks like Mail.app treats "non-standard" ports differently.  On the
>> standard port (993), the "SSL" option seems to do pure SSL; but with 
>> another
>> port specified, it does clean-plus-starttls (and hence fails horribly, 
>> because
>> it's talking to a pure SSl service)
> Is there anything I can do to get MacMail to behave correctly?  Or will 
> it clear up when I shut down UWIMAP and give Dovecot the default ports.  
> A Bronx cheer for Mac Mail........

It's possible it *might* clear up when you move to the standard ports; 
the server advertises STARTTLS capability (well, at least my Dovecot 
build does :) ). so it's possible that the Mail app is sniffing the 
server CAPABILITY flags, seeing a non-default port and trying to do 
something smart. I found this blurb:

"Apple’s Mail application has checkboxes to enable TLS for incoming 
Internet Message Access Protocol (IMAP) or outgoing SMTP connections. 
STARTTLS or direct TLS is used automatically, depending on the target 
port." (http://sial.org/howto/openssl/tls-name/)

If you have tcpdump (or similar) on one of your OS X boxen, fire it up 
and trap the packets between the two servers and check out the net 
traffic and what ports it's trying to use. That'd be where I start...

Also, check out this blog post:

"So, it appears that Mail.app does indeed support STARTTLS for IMAP, but 
only if you set the port number back to 143 after checking the “Use SSL” 


Troy Engel | Systems Engineer
Fluid, Inc | http://www.fluid.com

More information about the dovecot mailing list