Outlook 2010 (prior to SP1) contains an issue that corrects a sending issue when you have multiple addresses synced in a Profile and you are unable to click on a mailto link.
This ends up boucing the email back from your other addresses’s Exchange server, disallowing you to send from your POP/IMAP account under your different email address.
At the time of this writing, Apply Hotfix 2584053. Previous was: 2544027
Additional information here: http://support.microsoft.com/kb/2546733
Manually edit the following Registry key:
- Click Start, click Run, type regedit in the Open box, and then click OK. (Run from an elevated command prompt.)
- Locate and then select the following registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Options\Mail On the Edit menu, point to New, and then click DWORD (32-bit) Value. Type NewItemsUseDefaultSendingAccount, and then press ENTER. In the details pane, right-click NewItemsUseDefaultSendingAccount, and then click Modify. In the Value data box, type 1, and then click OK. Exit Registry Editor.