Today I have encountered a very strange message that I do not know the answer to. All of a sudden a pop up box mail is asking me for my Apple mail password. I put it in and it gets rejected. it just tells me "unable to varify account name and password". This is very strange. I know I don't have the wrong Apple ID password put into mail for the icloud/apple mail account in Mail. I know this because I can log into icloud via safari and suffessfully send emails that way. Mail can receive emails perfectly well. I just can't send any. Also mail tells me that the Apple Mail outgoing server is offline. This is very annoying. Being unable to use Mail to send emails due to this. Is there a fix for this issue?  I can send emails via my iPhone also. it's only mail on Mac OS 10.13 that seems to be broken. [edit 2] Solved. What I had to do was go into the system prefs and totally turn off my icloud account there. Then go back into mail and add an icloud mail account there and when it asked me to re-enable my icloud account on the Mac say yes and I went through the steps. I did it all through Mail. That seemed to do the trick. Hopefully the issue does not crop up again.