If your account is set up as POP, the sent messages are stored only on the local computer in TB. If it's IMAP, they are stored on the mail server and synced with the local computer, and any device on which the account is set up as IMAP.

Check Tools/Account Settings, Server Settings/Server Type to see if it's POP or IMAP.

Thanks. I originally set the account up as POP however I have changed it to IMAP (per online instructions) however this has not helped. I dont want to delete the account and recreate it as I am afraid I will lose all my sent emails. Any other suggestions? Thanks

re :I originally set the account up as POP however I have changed it to IMAP (per online instructions)

You cannot simply change server settings of a pop account. So I presume you created a new mail account and set it up as IMAP. Please Confirm that you did this.

Have you subscribed to see the imap mail account server Sent folder ? In 'Account Settings' > 'Copies & Folders' for imap mail account, did you select to use that imap mail account Sent folder? For example: Select: 'Place a copy in' Select 'Other' and choose the subscribed Sent folder on the imap mail account

Before you delete the POP account, copy the mail folders to Local Folders if you want to keep them. Then, add the account as IMAP, and subscribe to the relevant folders.

http://kb.mozillazine.org/Convert_a_POP_account_to_a_IMAP_account

Hi, Thanks for your message. I thought I did have it set up correctly. I have attached a screenshot. Do you think this looks correct or do I need to change something?