I have the same error when sending email to one mail address.
errors:
Reason: This is an automatically generated Delivery Status Notification.Delivery to the following recipient(s) failed after 1 seconds: * info@xxxxxxxxxxx.Error: * ?? ??
@PeterFeng -- there are a few reasons for the "non-delivery":
the intended recipient switched from TELUS to some other Internet Service Provider;
temporary problem with TELUS's mail-service, i.e., it was rebooting;
TELUS has been migrating customers' E-mail from TELUS-operated mail-servers onto GMAIL-operated mail-servers, one-by-one. You could have hit the "window" for which that ID was in the midst of migration.
TELUS has suspended services to the recipient, due to non-payment.
TELUS has suspended services to the recipient, because the customer's E-mail ID has been "hacked".
TELUS has suspended services to the recipient, due to a court-order -- probably some criminal charges could be underway, such as harassment, illegal drug-manufacture or sales, or distribution of NSFW material.
Use some alternate method to contact the recipient, to get a first-hand explanation.
