Thunderbird connection log

Posted on 2014-11-30
Last Modified: 2014-12-04

I'm configuring Thunderbird under Windows 7 to connect via StartTLS. I would like to view a log of the connection in order to a) debug configuration settings, and b) make sure that it actually is connecting via TLS and accepting certificates correctly.

It appears that there is no native log in the application. Did I miss it?  

If there is no log, would a viable approach be with a packet sniffer - and which is the easiest to use?

Thanks much,
Question by:fredo783
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Expert Comment

by:Dave Baldwin
ID: 40473095
I don't see a log mentioned.  I just set up a 'secure' email on my Comcast account and it 'automatically' set it up for SSL/TLS.  Apparently Comcast POP3 is one of the 'known' email setups in Thunderbird although I could have chosen IMAP.  I'm pretty sure that it did work because my Avast anti-virus intercepted it and I had to accept the 'security exception' caused by the Avast self-signed certificate.
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Expert Comment

by:Dave Baldwin
ID: 40473098
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Accepted Solution

frankhelk earned 500 total points
ID: 40473700
For packet inspection, I generally use Wireshark.

Open Wireshark, choose "capture options" from the menu, select the appropriate network interface and, presuming as IP of the distant mailserver, apply a capture filter of


That would limit the captured data to the conversation between your station and the mail server.

Capture the entire conversation when sending a test mail. Inspect the packets. If you could recognize text from your message in the lower pane, it's unencrypted. If it looks like completely junk, it's encrypted. If you see "SSL..." or "TLS..." as protocol in the packet list, the connection seems to be encrypted with SSL.

Right click on one of the packets and choosing "Follow TCP stream" will show the conversation concerning the stream the packet is part of.

Author Closing Comment

ID: 40477670
This is a perfect solution. By using Wireshark I was able to determine that TLS was used and that connection was encrypted. Your tips on using Wireshark were very helpful. Thanks! (By the way, Wireshark is quite easy to use. )
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Expert Comment

ID: 40480604
You're welcome :)

Wireshark's ease of use depends on how familiar you're with such things as networks, TCP/IP, Ethernet, etc, I think. Maybe I've underestimated your skills - sorry for that ;-)

By the way, Wireshark is a basic tool for many network / data flow associated problems, and I use it regulary for such things. A good advice in such cases ... follow the data ...

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