I’ve heard a lot of complaints about Outlook 2010 crashing on a reply or forward. This is caused by not having a folder set as the default delivery location for the account.
With Outlook closed, go to Control panel, Mail and select Show Profiles.
Select your profile and click Properties button, then E-mail Accounts.
On the E-mail tab, select your POP3 account, and then click Change Folder button and select a delivery folder.
You can also do this from within Outlook by going to File, Account settings and making the change on the Email tab. You will need to restart Outlook.
Outlook crashes when you try to send email messages because of a nonexistent delivery location setting in your profile
Published August 10, 2010. Last reviewed on January 19, 2013.