Mail on my Mac keeps asking for my mail passwords

I have 5 mail accounts. Since upgrading to new 2019 MacBook Pro with Mojave, mail often asks for password to my mail accounts even though they are correct in keychain. I check my email and it seems to be working fine. Is there any way to stop the prompts for mail passwords after MacBook wakes from sleep mode. I am on a fast home wifi. Maybe Mail app is timing out before home wifi is properly established???