Apple mail with multiple accounts, sender not correct I have multiple accounts set-up on my iMac.  I'm running the latest OS X Sierra.  

When I draft an email I select the account and this updates the sender email address, all is good.

However when I send the email, the email is sent not from the sender that was displayed whilst drafting the email but from the first account in my list.

Why?  Can I fix this or is it a bug?
I posted this same question to the Apple community and yesterday I got an answer which has solved the problem.

https://discussions.apple.com/thread/7956716