550 5.1.1 No such user h34si1677928wxd

If I try to email flamingomiami.com from my cendyn.com or tipsontripsandcamps.com domain I get the below undeliverable message.  However I can email that address and get a reply from the recipient using AOL or Yahoo.
Unknown user: bkoning@flamingomiami.com
RCPT TO generated following response:
550 5.1.1 No such user h34si1677928wxd
We use Ipswitch Imail.  2 versions  Imail 8.22 and Imail 2006.21
Thank you.
Who is Participating?
Computer101Connect With a Mentor Commented:
PAQed with points refunded (500)

EE Admin
try to put the domain name you try tpo send mail to to the white list of your antispam product
Which Server is generating the report ? Please add full NDR (w/o) email address.
Cendyn2007Author Commented:
Thank you. It turned out that the domain we were sending to did not have their MX records set up correctly.  Their primary mx record was resolving to an IP address and not an A record..
As they did not want to fix this I had to add all their 6 mx records and addresses to our hosts file and then we were able to send successfully.
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.