550 Access denied – Invalid HELO name (See RFC2821 4.1.1.1)

550 Access denied – Invalid HELO name (See RFC2821 4.1.1.1)

How to fix:

This error means that there is no reverse DNS lookup for the domain sending the helo.
To fix this setup your hostname correctly with a valid host.domain.com and go to the authorized DNS server for that domain and create an A record which points to the corresponding IP Address.

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Published on: Mar 03, 2021