Bounce-Mail Error: 554 5.7.1 xxxxx@xxxx.xxx: Recipient address rejected: SMTP AUTH is required for users under this sender domain

1. Someone wants to send you a message, but received this error message.

This error essentially means that our server has refused to accept the email message from the specified sender email address.

The reason for this rejection is that the email address of the sender of this message includes a domain that is maintained on a Mailix mail server, but this message was not sent from a Mailix mail server. We then assume that this is a forged abusive message. Spammers often use identical To: and From: addresses.

This error message should not happen often, because most mail providers have set their servers in a way that only sending with sender addresses maintained there is possible. However, there are still some (lazy and therefore insecure) Internet access providers that still allow sending mail with any real or faked sender address from their mail servers.

If the mail is legitimate, you can quickly fix the problem by requesting the sender to send the message through the SMTP mail server assigned by Mailix and not the one assigned by the Internet access provider.

2. You want to send a message to someone and you receive this error message

1. You might have setup and use the wrong SMTP mail server for your Mailix mailbox yourself. Please only use the outgoing (SMTP) mail server assigned by Mailix to send messages with email addresses maintained by Mailix. Sending messages via any other mail server will cause delivery problems in any case.

2. You want to leave Mailix and the domain of your e-mail address is already managed by a new e-mail provider. However, since you are still sending your message through Mailix, the new provider refuses to accept the message. As a general rule, you must always send your messages via the email provider that currently manages the domain of your sender address.