How To Enable Offline Mode In Thunderbird

The Offline mode in Thunderbird is useful lets you compose emails and also download and read previous messages.

Here is how to use it:

To go offline, click on File >Offline.

accessing Thunderbird offline mode

Then select Work Offline.

work offline option in Thunderbird

So, the icon at the bottom of the Thunderbird window will change indicating that offline mode is now enabled.

Thunderbird offline mode enabled

During this mode, you can still draft email messages. Click on the Write button as before. However, the option to Send will now be changed to Send Later.

send later option when trying to send messages in Thunderbird offline mode

This is because messages composed in offline mode will be in the Outbox until the online mode is back again.

outbox containing unsent messages during Thunderbird offline mode

Only after Thunderbird is online again, these messages will be sent.

You can also change how these messages will be sent by changing the Offline mode settings.

option of sending unsent messages when online mode is back in Thunderbird

So, to get a prompt every time to send these messages once online instead of directly sending them, go to Tools > Options.

accessing Thunderbird options

Then click on General.

General Thunderbird settings

Scroll down to the Network & Disk Space section, select Offline to bring up those settings.

accessing offline mode settings in Thunderbird

Then, enable the option of Ask me to receive a prompt to allow sending of messages from the Outbox.

toggle between online and offline modes and configure prompts for offline mode in Thunderbird

You can also receive a prompt for downloading messages before switching to the offline mode every time from here.

prompt to download messages in Thunderbird before going offline

Other than that, you can also choose between going online or offline everytime Thunderbird starts.

prompt to choose online or offline mode in Thunderbird on launch

This is by changing the Manual state when starting up settings.

changing Thunderbird manual state settings

All done.

  1. Dennis G Allard says:

    This article does not explain how to keep all email messages off-line. In other words I would like to in store my entire history of email and keep it all cached off-line. Spent over an hour searching the web to see if this can be done either in Gmail or with some other IMAP email client and so far I am unable to find any clear explanation of whether this is possible or not possible. It should be possible.