duplicate e-mails in my outlook sent items folder

[peterbowen1]

I have my Yahoo e-mail linked to my MS Office 365 outlook account; whenever I send an e-mail it ids duplicated in my sent items folder and the recipient is only receiving one e-mail?

[jayach]

I recall this being asked before, but can't remember what we suggested.

However a similar question was asked on Microsoft, so see if the answer given there helps.

Stop duplicating SENT emails - Microsoft Q&A