Thanks. Yeah, that's what I thought. So I guess I will tell him to live with the fact that only the new mails will be possible cause I've seen not much info on IMAP on his webhosters pages.

I've been using Pegasus Mail like forever with POP3 and told everyone I know how great it is. Many have switched to Thundbird in recent years though and but of those remaining faithul to Pegasus, one friend wants to switch to IMAP so he can access mail from his Android Smartphone. He asked me to do the migration but I haven't used IMAP so far. I know that he's lazy so he keeps all the attachment which results in a hugh mail folder. Is there any how-to on how to migrate an existing POP3 mailbox to IMAP? And what are the downsides? Thx.

[quote user="First_Moon"]I've been using Pegasus Mail like forever with POP3 and told everyone I know how great it is. Many have switched to Thundbird in recent years though and but of those remaining faithul to Pegasus, one friend wants to switch to IMAP so he can access mail from his Android Smartphone. He asked me to do the migration but I haven't used IMAP so far. I know that he's lazy so he keeps all the attachment which results in a hugh mail folder. Is there any how-to on how to migrate an existing POP3 mailbox to IMAP? And what are the downsides? Thx.

[/quote]

I have been using IMAP for quite while now but I'm by no mean an expert (so don't take this as a definitive answer)

Once the incoming mails (POP3) are on the client side, they are typically deleted from the server (unless configured differently).

As long as your friend's email provider supports IMAP, switching to IMAP is just a matter of knowing the IMAP server's parameters. Then he will be able to access all new mails since you got the setup working.

The downside of IMAP is slow speed. It trains you to keep your inbox clean. The bigger it gets, the slower it becomes. And when you want to search something, you need to download the whole freakin thing.

Good luck.