Well next time something fails, check the logs and see what happens.

If it doesn't happen again, it means that for some reason you need a more robust way to send emails, like this plugin (or some other simpler).

 Sometimes it is needed because of several technical limitations of hosting or the receipient servers.

@Anonymous20

Will do! Thanks again for all your help. I appreciate it.

I will monitor, and if there are any future failures I can't interpret, I will call on you.

Have a good day.