Thunderbird Unable to Connect to Xfinity IMAP Server with SSL/TLS When Using Bitdefender VPN

Hello Community,

I hope someone can assist me with this persistent issue with Thunderbird while trialing the Bitdefender VPN client for my internet security. When I launch Mozilla Thunderbird, it connects to my Xfinity email account without any problems. However, Thunderbird displays an error message after a certain period, stating it can't connect to the Xfinity IMAP server. The error details suggest that the app cannot establish a connection. If I use another VPN client, I never see this issue. Since the problem does not happen during the Thunderbird's initial load, I would guess the VPN client uses IP address ranges eagerly throttled by the IMAP server's IDS/IPS algorithm.

To elaborate:

  • VPN Client: Bitdefender
  • Email Client: Mozilla Thunderbird
  • Email Provider: Xfinity
  • Error: Unable to connect to IMAP server

This connection issue disrupts my email workflow, and I can't seem to find a solution on my own. Has anyone else encountered a similar problem, or can you offer guidance on resolving this issue? As a workaround, I added a Split Tunneling exception for Thunderbird. Any insights or suggestions would be greatly appreciated.

Thank you in advance for your assistance!


  • Hello @mostlylogical,

    Based on your description of the situation encountered, I would recommend contacting the Technical Support Teams, as more information might be required to troubleshoot this. You can get in touch with our engineers by choosing one of the contact channels available here:

    Let us know how it goes.


    Premium Security & Bitdefender Endpoint Security Tools user