Microsoft and Gmail are refusing our emails

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Microsoft and Gmail are refusing our emails

Post by superdrivesam » 2019-09-04 10:31

Our SPF, DMARC, and DKIM all pass with flying colors at any 3rd party site, such as MxToolBox and I can send emails to all O365 tenants, but emails to,, and, and TrendMicro ALL end up no where. Not even an NDR. Here is a header of an email sent to an O365 tenant:

spf-permerror (sender IP is
domain of used an invalid SPF mechanism

At the same time, here is SPF test results from MxToolBox:

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Re: Microsoft and Gmail are refusing our emails

Post by RvdH » 2019-09-04 11:32

Hard to help you to find the issue without the actual domain name and/or IP address
CIDR to RegEx:
DNS Lookup:
DNSBL Lookup:
GEOIP Lookup:

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