Mac Mail Sending Problems

Greetings Folks!

I've been experiencing a reoccurring problem with my MBP and the mail app that is increasingly getting more aggravating!

I have a bunch of emails set on my mail app and for some reason, for every 4-5 emails I send out I get a message saying that I mail cant send my email & I should either choose another outgoing server or try later. No matter what server I choose, I get this error message. the only way I can send emails once this message appears is to quit the mail app and then launch it again. Once the mail app is launched again, the mail sends automatically and immediately.

What am I doing wrong here. I've used connection doctor and my connections test fine.

Any help would be greatly appreciated!

thanks in advance!

 

anyone? pretty please?