Webform Emails Won't Send

Hello,
I'm hoping someone can help me with an issue I'm having.

Webforms from Thermotron.com have not been working properly since Tuesday. A few forms going to info@thermotron.com wen through but none that were going to customerservice@thermotron.com or softwareupdates@thermotron.com.

To troubleshoot I did the following:
1. Sent an email from my jnewton@thermotron.com account to both customerservice@thermotron.com and softwareupdates@thermotron.com to make sure these email accounts were working. I received confirmation responses from both.
2. I changed the forms that were going to customerervice@thermotron.com to info@thermotron.com (because Yesi said she was receiving those), now all forms (including info@thermotron.com forms) have stopped sending to her. I also changed softwareupdates@thermotron.com to rfarrell@thermotron.com (same person who receives the softwareupdates@thermotron.com) to test that and he didn’t receive them either.
3. I’ve sent test emails from both my PC as an administrator of the site and as an anonymous user from my phone to multiple forms as a test. No emails were sent.
4. I have not changed or updated any modules this week. (An updated SMTP module was the problem last time.)
5. I have emailed the person who created our site telling her our problem and she said she’s never heard of this problem, but just to make sure nothing has changed on the corporate end with emails. She’d think about other solutions as well.

The good thing is that the submissions are logging and customers aren’t getting an error response.

Any ideas would be fantastic! Thanks.