Starting around 4/16/2020 we started getting these notifications -
This is the mail system at host smtp.shopify.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <clients email address>: host gmail-smtp-in.l.google.com[22.214.171.124] said: 550-5.1.1 The email account that you tried to reach does not exist. Please try 550-5.1.1 double-checking the recipient's email address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 https://support.google.com/mail/?p=NoSuchUser n11si226707uap.224 - gsmtp (in reply to RCPT TO command)
Since I noticed them I've kept track and there have been 56 and these are all valid email addresses, from existing clients who have more than just 1 order in the system. I need some advice please & thank you.
We've been getting similar errors. Today it was something about limited IP reputation, which is very worrisome. What is going on?
<CLIENT EMAIL>: host hotmail-com.olc.protection.outlook.com[126.96.36.199] said: 451 4.7.650 The mail server [188.8.131.52] has been temporarily rate limited due to IP reputation. For e-mail delivery information, see https://postmaster.live.com (S3113) [BN3NAM01FT042.eop-nam01.prod.protection.outlook.com] (in reply to MAIL FROM command)