Configure SMTP port 587:

By following these steps Outlook 2010 will use port 587 for receiving and sending instead of port 25. This way you can, no matter which provider, always send emails. This is useful for example if a laptop is used differently at home than at work.

1. Open Outlook 2010 and go to 'File>Info>Account Settings'
2. Double click your account, check if all details are filled in correctly and click on 'More Settings'
3. Now go to the tab 'Outgoing server' and make sure both 'My outgoing server (SMTP) requires authentication' and 'Use same settings as my incoming mail server' are selected.

   

4. Go to the Advanced tab and change the 'Outgoing mail (SMTP)' from 25 to 587.

   

5. Save the new settings and click 'Test Account Settings'. When everything is set correctly you won't get any errors