It is important to manage your mailboxes, particularly your In / Out and Sent by limiting the number of messages you have stored in these mailboxes. IS advise you to keep very active mailboxes to a small size. For IMAP users you are advised to split up your mailboxes if they are larger than 20Mb in size . This can be done by creating additional mailboxes/folders and moving messages into them. For example your Sent Items can be split into 'sent2004', 'sent2005' with this years mail in your usual Sent Items mailbox.
The steps below explain how to transfer your messages to different folders. If you are unsure how to create new mailboxes in Thunderbird, then you should learn about how to do this first (see link in box at top of page).
To move a message or a group of messages you need to select the messages you wish to move then use the move to option by right clicking on the selected messages or under Message on the menu bar:-
Selecting adjacent e-mail messages:-
- Hold down on the shift key.
- Click the first message in the list, then click the last message in the list.
- Release the shift key. All adjacent messages are highlighted.
Selecting non-adjacent e-mail messages:-
- Hold down the Control key ([CTRL] key).
- Select the messages that you wish to transfer by clicking on them individually with the mouse.
- Release the CTRL key.
Transferring your selected messages:-
Once you have selected your messages you either right click on the selected messages and use the move to option and select the mailbox you wish to transfer the message to. Alternatively you can click on Message on the menu bar and use the move option and select the mailbox you wish to transfer to.