Email is stuck in queue

I have been using the same email setup (Samsung's) for at least 12 years on my galaxy phones with no problem.  About 6 months ago this problem started.  It works for a while and then only sending fails.  This is indeed a Comcast issue.  It's part of a Comcast "security" update that causes periodic rejections to, in this case, Samsung's email, although the original setup was automatic and worked fine.  If I delete and recreate the Comcast account, it works for about a month and then I have to repeat that process.  This is information I got from someone who is familiar with Comcast practices.  They aren't going to fix it.