so do you have an email address at mytrip-to-india.com as an employee?

Yes I do have sir. [email]@mytrip-to-india.com

See if extending the timeout works.

• Menu app icon > Options
• Select 'General'
• Scroll to the very bottom OR use the search : type 'Config' - see image below
• click on 'Config Editor' button
• Accept the risk :)
• type: tcptimeout

look for this line: mailnews.tcptimeout

• Right click on that line and select 'Modify'

The default Value should be 100.

• Suggest you increase to 1000
• Click on OK

This may also be caused by your Anti-Virus software who may also control the Firewall.

In your Firewall settings, Thunderbird must be an allowed program.

What Anti-virus product are you using?

If you are using ESET/NOD32 security/AV then probability is very high it is causing your problems. According to their forums, you should temporarily disable SSL until they solve the problem per https://support.eset.com/en/kb3126-disable-ssl-filtering-in-eset-windows-products?ref=esf - the problem is being reported by dozens of users https://forum.eset.com/topic/26517-problems-with-thunderbird-and-imaps/ https://forum.eset.com/discover/

To see if Anti-Virus is the problem... Restart computer in 'Safe mode with Networking' Then start thunderbird.

I also wondered if this was being caused by the server not using up to date TLS.

If the above comments did not work...No harm in trying this as it is easy to reset. This is what you need to do in Thunderbird to reset the minimum setting.

• In Menu app icon > Options
• Select 'General'
• Scroll forever to the bottom OR use search - click on 'Config Editor'
• accept the risk
• In search type: tls.version
• look for this line : security.tls.version.min
• Double click on line to open an edit window and enter the number 1
• click on OK.
• Exit window - top right x

Exit and restart Thunderbird.