So my wife wants me to create a forward(or list) of email addresses that she can send to for company wide mailings. IE email@example.com, so she would send an email to firstname.lastname@example.org and 100 people would get this email. However her company email guy will not create a mailing list for her for whatever reason, so I said i can create a froward using one of my domains instead and just forward to all the emails she wants for her company. Seems simple enough, but it does not work?? This is what is happening... I create a forward named, company_name@another_domain.com, I added the list of users, all with @domain.ca, so email@example.com, firstname.lastname@example.org and my email address email@example.com, as a test recipient. Now as a test i send an email to company_name@another_domain.com from my personal email(firstname.lastname@example.org), which uses an external mail server or any other mail server other than domain.ca's exchange server , yahoo, google, whatever, all works as expected, everyone get the emails just fine. See logs below.... Feb 10 07:52:44 mail2 postfix/pipe: 4E4C5B0013C: to=<email@example.com>, orig_to=<company_name@another_domain.com>, relay=dovecot, delay=0.3, delays=0.04/0/0/0.26, dsn=2.0.0, status=sent (delivered via dovecot service) Feb 10 07:52:45 mail2 postfix/smtp: 4E4C5B0013C: to=<firstname.lastname@example.org>, orig_to=<company_name@another_domain.com>, relay=mail.domain.ca[38.111.xx.xx]:25, delay=1.1, delays=0.04/0.03/0.45/0.57, dsn=2.0.0, status=sent (250 Ok: queued as 5EA90115035B) Now if my wife sends an email to the same forward, company_name@another_domain.com from her internal (microsoft exchange, which is the mx for domain.ca)server, all the emails bounce, except the one to me, email@example.com???????? If she sends an email using gmail from the same computer it works??? For troubleshooting purposes, i revised the list of emails and kept it short having one email for firstname.lastname@example.org, in this case email@example.com and my email firstname.lastname@example.org, See below for logs... Feb 9 15:24:07 mail2 postfix/pipe: A1B6FB0012B: to=<email@example.com>, orig_to=<company_name@another_domain.com>, relay=dovecot, delay=0.36, delays=0.08/0/0/0.28, dsn=2.0.0, status=sent (delivered via dovecot service) Feb 9 15:24:07 mail2 postfix/smtp: A1B6FB0012B: to=<firstname.lastname@example.org>, orig_to=<company_name@another_domain.com>, relay=mail.domain.ca[38.111.xx.xx]:25, delay=0.67, delays=0.08/0/0.42/0.16, dsn=5.0.0, status=bounced (host mail.domain.ca[38.111.xx.xx] said: 550 Sender email address rejected (in reply to RCPT TO command)) So "550 Sender email address rejected" which sener?? email@example.com or the forward of company_name@another_domain.com ??? my wife Paula has not problems sending emails to anywhere with the same exchange server. Is this weird error caused by some stupid config on the exchange server? Any help very much appreciated! Thanks and have a great weekend!