iphone email stays in outbox says wrong password. mail works on desktop

iPhone 8: twice in the last month, my outgoing mail server on the iPhone has failed to send messages. the same message works fine on my desktop. last time I spent hours with Comcast to fix the problem which they couldn't really explain although they did somehow resolve the issue that time. This time, I wonder if there is a fix I could do. additional info: I reset my password, as the message said that was the problem, but that did not resolve issue. I have shut down and restarted w/o success