This seems to be an issue when you upgrade to windows 10 that you cannot send emails with a POP3 account. The recommend solution is to run the following command as an administrator and the reboot your computer. Make sure Outlook is not running when you run the command
sfc /scannow
This fixes the majority of peoples setups.
Outlook 2013
I have a client who could not send from a POP3 account at all but then has performed the above command. He still cannot send emails from a POP3 account normally but when he exits and restarts Outlook as an administrator, those POP3 emails will send.
Notes
- There was an PDF addon causing issues/conflicts in outlook but this made no real difference
Client's setup:
- Windows 10 (pre 1511)
- Outlook 2013
- Single Profile
- Main account account is a Hosted Exchange account
- Secondary Account is a standard POP3 account
Things not Tried so far
- Delete whole profile and re-create
- Run pop3 and exchange accounts in different profiles
- Remove office ecommpletely and re-create
- Make sure all windows and office updates are applied, including the major windows update that has just come out
- Update to the new Windows 10
- Apply all office 2013 updates
- Change outlook version