For Outlook Express and Windows Mail:
Select menu Tools/Accounts and select your e-mail account. Press Properties button and select "Advanced" tab.
In Outgoing mail (SMTP) box type 26 and press "Apply", "OK" and "Close" buttons.
For Outlook 2003/2007
Select menu Tools/Account Settings. Select your POP3/IMAP account and select "Change" button
Press "More Settings..." button. Select "Advanced" tab
In Outgoing mail (SMTP) box type 26 and press "OK", "Next", "Finish" and "Close" buttons.