KMail In Depth - page 2
Masses Of Features and No Malware
There are a number of ways to import messages from another mail client. IMAP is easy, because the message store and folders remain on the server. All you do is enter the account information in KMail: Settings -> Configure KMail -> Network -> Receiving -> Add. Check "IMAP" and click OK. This brings up a menu with three tabs: General, Security, and Filtering. The General options are self-explanatory. On the Security tab, click "Check what the server supports" to have KMail automatically identify whatever security the server supports. On the Filtering tab you can tell KMail to use your Sieve filters, if you have any.
Be sure to remember the Security tab--if your server encryption ever goes haywire, you can set your login to "None" and still fetch your mail. Non-securely, of course.
Migrating your POP folders from another mail client depends on what format the old mail client uses. mbox, the old Unix standard, is easy: Tools -> Import -> Import mbox Files.
Maildirs are easy; simply copy them to ~/Mail. Or you may point KMail to the folder containing your maildirs. First shutdown KMail. Then open ~/.kde/share/config/kmailrc, find the [General] section, and add a line like this: folders=/home/username/.foldername
A not uncommon problem is having both mbox and maildirs. (Right-click on your folders in KMail and click Properties to see what they are.) This is no big deal in ordinary usage, but for migration it's messy. The solution is to migrate each separately: copy over your maildirs, then import the mboxes. Another way to do this is to convert your mboxes to maildirs first. To do this, first create new maildir folders in KMail. Newer versions of KMail default to maildir; confirm this in Settings -> Configure KMail -> Misc -> Folders. And you can also select which format you want when you create the folder.
Next, copy the messages from the mbox folders into your new maildir folders. Verify that the copying worked, delete the old folders and you're done.