Dear Support,
I have tried emailing my contacts at my bank with domain @vietinbank.vn
All been rejected according to the copy past below, last week was still ok.
The bank is not the problem here as they did check the logs and have not seen the email arriving at their gateway.
How can I solve this issue, thanks for your help solving this crucial problem !
Best Regards,
Christian
========
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.
@vietinbank.vn
INVALID_ADDRESS, ERROR_CODE :554, ERROR_CODE :Transaction failed
Received:from [192.168.1.56] (118.69.182.236 [118.69.182.236]) by
mx.zohomail.com
with SMTPS id 1536139599518339.7010672014844; Wed, 5 Sep 2018 02:26:39 -0700 (PDT)