Hi this problem has bogged me down, and I noticed there were few these 550 5.1.1 errors already in forum. Unfortunately haven't found the solution.
This has do with one email address, which uses a 3rd party email solution provider: firstname.lastname@example.org, that gives me the error when I try to send from email@example.com. error message: SMTP Error (550): Failed to add recipient "firstname.lastname@example.org" (5.1.1 email@example.com: Recipient address rejected: User unknown in virtual alias table).
Background (this is probably important): Both example.com and ejemplo.com are hosted on my virtualmin, they were recently migrated here, so I wonder if there is a local conflict? In short:
Thanks for any insights! Definitely contacting my email provider for example.com, but I want to understand the underlying issue here.
thanks so much.
@rkan: Have you tried sending emails to firstname.lastname@example.org from a gmail\hotmail\yahoo type of account?
Thanks Dibs - and good point. Yes, I can send emails to other gmail/hotmail etc accounts, I can also receive email from email@example.com into the ejemplo.com account; the sending seems to be the issue here. I've done an https://mxtoolbox.com/domain/example.com/ check and their are no errors. I also used various other emails to send emails to example.com, and they work without the 550 5.5.1
For lack of a better way of describing it, could it be some sort of caching issue? If so is there a way to check this? It seems localised.
I'm slightly confused.
for 1-4, I used a gmail account and a google apps account to test.
@rkan - so from what you are saying:
Can you post up your postfix configuration? And for the example.com - mail is NOT enabled for that VirtualServer?
And for the example.com - mail is NOT enabled for that VirtualServer?
my god, after all that, this was the issue! I really appreciate your patience here, its an obvious rookie mistake.