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GrzeWier's avatar
GrzeWier
Copper Contributor
Aug 03, 2016

Support for RFC 7505

Hello

 

Are tere any news if (and when) Exchange Online plans to support https://tools.ietf.org/html/rfc7505 ?

RFC 7505 allows to define explicit null-mx record.

 

Gmail is already supporting this.

When I email a domain with null-mx record I instantly get this nice looking NDR:

Delivery to the following recipient failed permanently:

     user@domain.com

Technical details of permanent failure:
DNS Error: 33796847 DNS type 'mx' lookup of domain.com responded with code NOERROR
The domain domain.com doesn't receive email according to the administrator: returned Null MX https://www.rfc-editor.org/info/rfc7505

 

Email sent from Exchange Online will go into 'normal' pending/retry mode and after 48H generate standard "host unreachable" NDR.

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