If this is just the odd email then open email and click on the 'Forward' button and forward to gmail address. If you want to Forward specific incoming emails which are incoming to your 'Inbox' then you could use the Message Filters. Tools > Message Filters Click on 'New' Give suitable name Select 'Getting New Mail' Select 'Filter before Junk Classification' Select 'Match the following' - if setting only one condition OR if more than must be true Select 'Match any of the following' if you are setting more than one condition but ANY of them must be true. Set condition: eg: 'Subject' 'contains' 'specific text which you type' or: 'To' 'contains' and type your email address Set what to do: Perform these actions: 'Forward message to' and type your gmail email address. Click on 'OK' Make sure the filter is enabled. Remember - filters operate in the order listed - so you may want this new filter positioned at the top. I would also suggest you make sure the 'Filter log' has been enabled. The other alternative and some would say this might be more convenient because it does not rely on your computer being switched on and Thunderbird running - is to access your webmail account and set up a direct Forward of all emails to the gmail account. Basically get the server to send everything to the gmail server.