None of the system emails are sending (i.e. password reset). I contacted the server company(since this is happening on multiple sites) and found out the MODx is not putting in the emailfrom. I checked the system setting ‘emailsender’ and it has a valid email. Would really appreciate some insight. Thank you in advance.
That page shows some recommended settings and how to test things from MODX’ end. If it only affected forms it could be a formit configuration (an empty &fromName/&fromEmail) but this sounds like something that would be incorrect on the settings level.
PHP’s built-in mail() that you appear to be using is very poor for delivery, and having it blocked on the server is not even the worst of ideas as spammers love it too.
I’d strongly recommend switching to sending via SMTP, how to do so is also explained on the documentation I linked you before.