Thanks for the system ID's for looking up.
This doesn't appear to be related to My AutoSupport - there appear to be problems with the systems being able to send typical content-rich AutoSupports via the customer's SMTP servers. This is somewhat supported by the fact that the simple "noteto" e-mails are getting through without problems. It's likely to be an incompatibility with the customer's anti-spam/anti-malware/anti-virus scanning functionality in place for e-mail.
I'd open a support case for further technical assistance.