To use Mailstore with Outlook 2003, follow these steps:
Open Outlook, go to the "Tools" menu (if you get other pop-up screens when opening Outlook click the cancel button next to them until you can click on the "Tools" menu), and click on "E-mail Accounts..."
When the "E-mail Accounts " window appears, click on the circle next to "Add a new e-mail account " then click "Next".
Click the circle next to "IMAP" and then click "Next" .
This screen requires you to enter all your e-mail account information.
Your Name: Your Name
E-mail Address: firstname.lastname@example.org (any of your Pobox addresses)
User Name: email@example.com (any of your Pobox addresses)
Password: Your Pobox.com password
Incoming Mail server (IMAP): mail.pobox.com
Outgoing mail server (SMTP): smtp.pobox.com
Once you have filled out the blanks, click on "More Settings..."
In this window, click on the "Outgoing Server" tab and ensure that the "My outgoing server (SMTP) requires authentication checkbox" checkbox is checked, and the circle next to "Use same settings my incoming mail server" is filled.
Click on the "Advanced" tab, then check the box under "Incoming Server (IMAP)" and next to "This server requires an encrypted connection (SSL)". The port number next to "Incoming Server (IMAP)" should be 587. Do the same for the "This server requires an encrypted connection (SSL)" box under the "Outgoing Server (SMTP)" heading.
Click OK then click "Finish" on the window that confirms you have successfully entered all the required information.