I'm using thunderbird on my laptop to access my work email over imap (we're an MS Exchange shop but the server is configured for imap as well).

This works fine when I'm at work, but for some reason, since a few months, it doesn't work anymore at home. Thunderbird just sits there waiting endlessly, with no email ever getting downloaded. It has worked in the past but not since the last few months. I think the change occurred around the time that the server was switched from normal imap to secure imap, but I'm not 100% sure about that. I contacted the ICT helpdesk but they're saying everything is working normally on their end, so it's my own problem. But like I said, it's working fine when I'm at work, so the account configuration in thunderbird should be OK.

With a little experimentation I found that if I plug my laptop directly into the ADSL modem, it works normally. Only when my wireless router is between my laptop and the ADSL modem, the problem occurs.

The router in question was a Sitecom WL-176 storage router. I tried resetting to factory default settings, upgrading firmware, nothing. I also tried replacing with a D-Link DIR-615 router, no luck either.

So now I'm stumped. Any ideas? What else can I try to troubleshoot the problem?

I'm using Thunderbird version on Ubuntu 9.10

3 Answers 3


Try to resolve the host:

$ host mail.yourcompany.com

Then try traceroute:

$ traceroute mail.yourcompany.com

If that worked without anything abnormal, try connecting with telnet:

$ telnet mail.yourcompany.com 993

(I assume that 993 is the port used for secure IMAP.)

Then you might have a better idea where it's failing.


Perhaps ports and/or security settings have changed for outside networks, whereas internal net is still lower/same security? Or perhaps

Many companies require different settings for access from unsecured (i.e. not on the premises network).

Try Peter's tests, should reveal where your problem is at.


This happens to me constantly on my Comcast connection. The only solution I've found is to give your router a new mac address (cloning the PC MAC usually does the trick). Magically, the IMAP ports work fine ... for a while anyway.

This is not a matter of Comcast blocking my connection as they do with outgoing mail. to prove that yourself, remove the router all together and connect your PC directly to your modem, and you'd find the problem is resolved.

I've even tried upgrading my router, but eventually the problem returns.

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