I can’t receive mails on my mail account

Check here -> If you can't receive email on your iPhone, iPad, or iPod touch

If you can't receive email on your iPhone, iPad, or iPod touch - Apple Support

jeimy193 Said:

"I can’t receive mails on my mail account: I don’t know what to do"

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Use a New App Password:

Do you use an App Password? If so, try a new App Password. Sometimes, changes (i.e. updates) are made to the device, and then mail server syncing becomes an issue (which is what a new App Password it intended to fix). For example, go here for gmail: Sign in with App Passwords - Google Account Help - Google