Changing from ".Mac" account in Mail to "IMAP"

Question

When I orginally set up my primary Mail account on my laptop it was ".Mac", rather than IMAP or POP. I'm finding I can't fully take advantage of the Alias features. Another posting here explains that if I delete the existing ".Mac" account and build a new one as IMAP, I'd then be able to create alias email addresses. In the present configuration I can "create them", but they don't appear as available in the pull down menu when I send mail. I'm a bit reluctant to delete my present .Mac account in Mail because I get a warning that all my mail will go away if I delete that account. To complicate matters, I sometimes work on my iMac at home, and that one's set up just the same as a ".Mac" account. Presumably I'd have to change that one too? Or is there some way I can make setting up the alias addresses work while keeping my primary account as a .Mac account? Obviously I'm not relating conceptually to what's going on here!
Tom
PowerBook G4   Mac OS X (10.4.8)   Also have iMac dual core

Answer 1

I access my .Mac account as a .Mac type account with Tiger Mail and I use/access a single .Mac alias address at a time. I have no problems with the alias address being available as an address to choose from via the Accounts selection when composing a message.
Do you access more than one alias address at a time?
Does it make any difference when selecting Edit Email Aliases under the Email Address field available under the Account Information tab for the account preferences?
Since a .Mac account is really an IMAP type account and behaves in the same way, when deleting the account in Mail, no messages available at the server in the account's Inbox or any other server stored messages will be affected when deleting the account and re-creating it as an IMAP type account.
What you do lose when deleting an account in Mail are any locally stored mailboxes/messages for the account such as Drafts, Sent, Trash and Junk if these messages are not stored on the server.
If you don't store Sent messages on the server, before deleting the account you need to do the following:
Create/utilize an "On My Mac" location mailbox which is stored on the hard drive and not associated with any account. Transfer the account's Sent messages from the locally stored Sent mailbox for the account to the user created "On My Mac" location mailbox.
Delete and re-create the account in Mail as an IMAP type account. All server stored messages in the account's Inbox mailbox will be available again in the account's Inbox mailbox and after sending a message with the newly created IMAP account which will create a new Sent mailbox for the account, you can transfer the old sent messages from the "On My Mac" location mailbox to the new Sent mailbox for the account so no messages will be lost.