University Computer Help Desk

How to use offline mode in Thunderbird

You can use offline mode in Thunderbird when your computer is not connected to the Internet.

Before You Begin

Offline mode in Thunderbird allows you to read email messages you've previously received and compose new messages without having an active Internet connection.

Offline Mode in Thunderbird

To use offline mode in Thunderbird, do the following:

  1. Open Thunderbird and log in.
  2. To enter offline mode, do one of the following:
    • Click File > Offline > Work Offline.
    • Click the icon that looks like two computers in the lower-left corner of the window.
  3. You are asked, "Do you want to download messages for offline use before going offline?" Click Yes.
  4. Thunderbird enters offline mode. The icon in the lower-left corner will become a red circle with an X in it. This indicates you are in offline mode.
  5. You may disconnect from the Internet.

In offline mode, you can read email you've already received. You can also compose new email.

When you are offline, new messages you send are stored in a local folder named Unsent. Thunderbird will prompt you to send messages in the Unsent folder the next time you go online.

Online Mode in Thunderbird

Thunderbird must be in online mode to access the mail server. If you have messages queued for delivery in your Unsent folder, Thunderbird will prompt you to send them when you use online mode.

  • Each time you launch Thunderbird, it starts in online mode.
  • If you launch Thunderbird and there are messages waiting to be sent in your Unsent folder, you are asked, "Do you want to send the messages in your Unsent Messages folder?" Click Yes or No, as desired.

If Thunderbird is already open and you want to switch from offline mode to online mode, do the following:

  1. Make sure you have an active Internet connection.
  2. Click Get Mail.
  3. You are asked, "You are currently offline. Do you want to go online to get new messages?" Click OK.
  4. If there are messages waiting to be sent in your Unsent folder, you are asked, "Do you want to send the messages in your Unsent Messages folder?" Click Yes or No, as desired.

Off-campus users: If Thunderbird is configured with MailVPN settings, you can check and send email from both on campus and off campus. If Thunderbird is configured with typical mail settings, then you must connect to VPN before you can check or send email from off campus.