Server Response 530: 5.7.1 Authentication required - Receive Error

The error message 530: 5.7.1 Authentication required can have several causes. One of the most common causes of this error message is that the outgoing mail server is listed on a DNS Blackhole List (DNSBL).

DNSBL lists are also known as spam blacklist servers. The message was consequently rejected by our system.

You can check for yourself whether an IP or a mail server is on a DNSBL list, for example via a blacklist check. To check the IP address or domain, we recommend this tool, for example:

Enter the domain or IP address of the outgoing mail server. If the result is negative, contact the sender or the administrator of the outgoing mail system.

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