Mail app not downloading emails and showing account errors on iPhone

my mail app constantly is showing previews of my emails then when I open them , they say “this message has not been downloaded from the server”. As well as other accounts saying account error at the bottom and not allowing to receive new emails. Every one of my emails are not working on my mail app. I have already tried logging out and logging them back in. I’m at a loss

[Re-Titled by Moderator]

Original Title: Mail app errors