We have been using the tmomail.net e-mail to SMS gateway to send notifications for voicemails received by our corporate PBX. Sometime within the past few days, these messages started to get blocked. We are getting a 550 failure code with a "rejecting banned content" description. There have been some other threads that mention that we can get our domain whitelisted.
Best answer by srickar
I can help you with this. Please verify the sending envelope does not contain info@, postmaster@, test@, etc that are generic in nature. The reason these are currently blocked right now is due to recent phishing activity that is using generic envelope names asking users to reset their Facebook or Netflix passwords. If using an email username that is generic, please consider modifying to something that is unique and not shared with other email entities.