smtp remote host responds "550 Sender verify failed"

Solution 1:

This is not your fault. This is a fault of your recipient's server.

Doing "sender verify" is always a bad idea. You have to convince the recipient to stop this behavior as this is not a suitable antispam method.

• Read this to know how to do this in Postfix, and read between the lines why you SHOULD NOT do this as sender verification.
• Read this carefully to see WHY it is a bad idea.

But anything you do to fix it on your side is a waste of time.

Solution 2:

This is most likely because you are using a From field which differs from the actual mailbox account name.

Some SMTP servers are configured to reject such an inconsistency.

So, for example, if your real account name is [email protected], you cannot send emails as [email protected].