Is this a POP or IMAP mail account ?

Pop mail accounts will have the option 'automatically download new messages'. This is because POP mail accounts can only get access to server Inbox and download mail to Thunderbird Profile mail account Inbox mbox file. The emails are stored in Thunderbird Profile folder. There is no synchronising, you are not remotely viewing the emails on the server, so you have option to download or not.

IMAP mail account do not have that option. IMAP accounts see a remote view of the folders on server. It will show any folders you have subscribed to see. It will download headers only and when you select to view an email, it will retrieve that email off server so you can read the contents and store it in a temporary file. The email is not stored in thunderbird profile folders, so cannot be viewed in offline mode.

If you synchronise subscribed folders then a copy of the folder will be downloaded and stored in Thunderbird profile folders, but the folder is constantly updated/synchronised to show what is on the server. As there is a copy in Thunderbird you can view these emails even when using 'offline' mode.

I believe you have created an imap mail account. 'Offline mode' will stop any synchronising with server, but you would need to synchronise subscribed folders to see emails before you use this offline mode. You could choose to start up in offline mode and go into 'online' mode when you want to download.

How to go offline/online' mode quickly: Bottom left of Status Bar there will be a 2 blue screen icon. This means you are in 'Online' mode. Click on the 2 blue screen icon and it will change to 2 black screen icon - this means you are in 'Offline mode' Click on 2 black screen icon to swap back.

File > Offline > download/synch now will synchronise subscribed folders and then go into Offline mode.

More information on IMAP and synchronising subscribed folders.

• https://support.mozilla.org/en-US/kb/imap-synchronization

Offline settings: Tools > Options > Advanced > Network & Disc space or Menu icon > Options > Options > Advanced > Network & Disc space click on 'Offline' button

You can choose whatever settings you prefer...here are some suggestions. When starting up: select: Ask me for online state when starting up then you can choose to startup online or offline.

Send unsent messages when going online: Select: Ask me Just in case you do not want Outbox emails to be auto sent.

Download messages for offline use when going offline: Select : Yes

Yes, you are correct it is an IMAP mail account. Is it possible to delete the account and recreate one as POP? I have followed your very clear instructions as above, hopefully that will work now. Thank you for your time and expertise.

All the emails you see in the IMAP account Inbox are still stored on server. you can delete the imap account and it will not effect those emails. If you have emails in other folders, I suggest you move them into Inbox folder as Pop mail accounts can only access the Inbox to download emails.

To delete imap mail account: Tools > Account Settings or right click on mail account name in folder pane and select 'Settings'.

• select the imap mail account
• click on 'Account Actions'
• Select: 'Remove Account'
• click on OK

You can create a POP mail account. File > New > Exisitng mail account or Menu icon > New Message > exisitng Mail Account

• enter name, email address and password
• click on 'Continue'
• Thunderbird will attempt to locate server configuration
• Check - is POP selected
• Make sure POP is selected
• Use the 'Manual Config' button if necessary to make sure all setting are correct.
• click on 'Done' to create the Pop mail account.