Reset iCloud e-mail password.

Are you using a non-Apple e-mail application or an older OS? You may need 2 Factor Authentication or 2 Step Verification and an app specific password.

Apple ID -Two-factor authentication

Apple ID - Using app-specific passwords

Apple ID - Two Step Verification App Specific Passwords

Apple ID - Two Step Verifications FAQ

I am having the same issue. I have iCloud set up and I am using my Apple ID. Everything works on my iMac but I cannot reset the Apple mail account on other devices. I have tried the Apple ID password but it says it is wrong. So now I cannot check mail on my iPad or phone which means I lose valuable messages when on the move. Very frustrating. It's only this mail account that has issues other work ones are fine.

Please advise on how to reset my password across all devices where I am using Apple mail?

It should be the same as your Apple ID password.

See this -- If you forgot your Apple ID password - Apple Support.

That is what I thought but when the window comes up to put my iCloud password in, I use my Apple ID password and it says it is wrong. Any ideas?

What IOS are you using on your devices? You need IOS 9 or later.

I have the same issue. I have reset my 'Apple ID"password twice. My iCloud email is showing incorrect. I have 10.12.5 and the same error message occurs. Yes to the 2 step verification.

Are you using a 3rd party mail application? For that, you need an app specific password.

Yup, I have one of these too. :-

It's not the same password. I cannot get in either. This thread is no help either. I have 10.10.5, and a gmail account with a separate password.