backup mx no such user
Question asked by Richard Frank - 9/24/2019 at 5:25 AM
the situation is
mx1 of customer
mx2 as backup mailserver (incoming gateway for 1)
mx3 as backup mailserver  (incoming gateway for 2)

when a mailserver connects to 3 to deliver mail the server responds no such user.

it is solved when I add the IP nr on server 3 as incoming gateway.

my idea was to have mx 3 to send 't to mx 2 which does all the scanning.

Question, can mx3 be the fallback for the incoming gateways configures on mx2?

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Employee Replied
Employee Post

You may want to reference this post as it sounds like you may be experiencing a similar issue:

Richard Frank Replied
Hello Ben,

Thanks for pointing to that topic.
I have single IP addresses in my incoming gateways

other example

mail.soko.nl ( is configured as incoming gateway with domainforward to IP number of customer with his domain name
fallback.soko.nl is configured as backup MX for mail.soko.nl single IP nr


mail.soko.nl accepts mail for the domain
fallback.soko.nl responds with user unknown. It should accept the mail because it's the backup mx of

mx records

why doesn't fallback.soko.nl accept mail for the domain?

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