I recently set up email forwarding in Shopify to a Gmail account. All of my test emails have been undelivered with a rejection message similar to the one pasted below. The message below is from someone else’s community post who uses Hotmail. I use Gmail and get the same message.
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
< Name [email removed] hos
hotmail-com.olc.protection.outlook.com[ number 3] said: number The
mail server [ number ] has been temporarily rate limited due to IP
reputation. For e-mail delivery information, see
https://postmaster.live.com (S3113)
[SN1NAM02FT047.eop-nam02.prod.protection.outlook.com] (in reply to MAIL
FROM command)