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Office365 and a new IP address


Are you properly rate limiting and warming up the new IPs sending volumes
or just sending at normal speeds?

Are you properly authenticating your email with SPF, DKIM and SPF as per
the Postmaster page suggestions for sending email?

Are you properly enrolled in SNDS, Junk Mail Reporting etc...

More self help tips and how to contact MSFT for support can be found here:



On Wed, Mar 14, 2018 at 11:34 AM, Paul Reichart <paul_reichart at wiband.com>

> Wondering if anyone on the list has ever set up a mail filtering appliance
> or server on new IP address and had to deal with 451 messages from Office
> 365.
> We're processing a large volume of mail and seem to be throttled by O365.
> Seeing something like this:
> 451 4.7.500 Server busy. Please try again later from [x.x.x.x].
> (AS77713180) [.....outlook.com ].
> We own the IP block and the address itself is not on any block lists.
> It's been going on for a few days now, pissing off a lot of our customers.
> As expected O365's front line support is totally useless.
> Any advice would be appreciated!