smtp 550 permanent failure

How to fix email error “550 permanent failure blocked”

Please help! When I send mails to two of my friends, one of them never receives it and I get a mail bounce.

That was a recent support request that we received at our Outsourced Tech Support Services, where we resolve support queries for web hosting providers.

The hosting user kept on getting the error “550 permanent failure for one or more recipients” from one of her contacts.

Why did this happen? Let’s dive into the details: