I am on BT Yahoo mail using Outlook 2010 on a Windows 10 PC.
For the past couple of days (possibly longer!) all of the emails I send to gmail accounts fail to be recieved i.e. Outlook says they have sent successfully but they never get to their destination. All other email addresses work fine?
Sending from the same Outlook using a different email account (non btinternet) to gmail works fine. Sending from BT Yahoo web email system to gmail works fine. Sending from my Android phone to the gmail works fine.
So it looks to be something with the btinternet / Outlook combination that has stopped working.
Outlook is set up as POP3 using the mail.btinternet.com server.