Zentyal blocks my clients from accessing IMAP Mail on Webserver

[marbell41]

Since some time now, I always get a Timeout when trying to collect Emails with Outlook, Mail or Thunderbird via IMAP behind my Zentyal Gateway.
I've already scanned trough some Posts here in the Forum and did apply a Firewall Rule to allow outgoing HTTPS traffic.
(by creating a HTTPS Service with Destination Port 443 and applying it to the "Filtering rules for internal networks" section)

Also im able to telnet for example imap.gmail.com 993 on the zentyal machine, but not on the client.
(here it yields:

telnet imap.gmail.com 993
Trying 173.194.70.109...
telnet: connect to address 173.194.70.109: Connection refused
Trying 173.194.70.108...
telnet: connect to address 173.194.70.108: Connection refused
Trying 2a00:1450:4001:c02::6c...
telnet: connect to address 2a00:1450:4001:c02::6c: No route to host
telnet: Unable to connect to remote host)

Whereas on the Zentyal machine it yields:

telnet imap.gmail.com 993
Trying 173.194.70.109...
Connected to gmail-imap.l.google.com.
Escape character is '^]'.

Attached you find a snippet of the Firewall Log, note the outgoing and dropped packages to Port 443.

Would be great if somebody could provide a hint how to solve my problem.
(Client is running OS X)

[christian]

I'm afraid I can't really help but will ask a perhaps silly question:
- why do you ask about IMAP and show HTTPS ?

Then stupid additional questions:
- did you already authorized port 993 from your LAN to internet ?
- why not using POP relay instead of IMAP (I know this doesn't solve your problem but I'm just curious)
- mail retrieval from Zentyal is another option 

[marbell41]

The HTTPS thing came up somewhere here in the forum with a similar issue so i just gave it a shot.
And it seems as if i had at some place deleted the IMAP Rule so by adding it again and adding a rule for Gmail's SMTP port everything now seems to be working fine again.
So you did actually solve my problem THX
And why use IMAP? It's really just a personnel preference.

[christian]

So if you problem is magically solved, could you please update first post and stamp it as [SOLVED] 

[marbell41]

Okay Today Problem resurfaced without changing Zentyal configuration.