I'd have to see an example of one that doesn't work. Ripping it out and adding it back wouldn't change anything. The key is finding the problem before trying to fix it. Maybe a particular company doesn't work or particular entries in the form cause issues.
I suppose we could start logging the debug data for each email attempt to help debug it if you can't figure out the steps to reproduce. You could try to find the SMTP server logs to see if there is anything there. You are using an external smtp server, so I'm not sure if it is in your cPanel or if it is from another server entirely that handles your email.