Spam Filter Blocking or something on users side of things?

Question

Spam Filter is designated some email as blocked. This sender has sent us email in the past. The reason it was blocked was:

"Domain of tbu****s@mc**-ar**.com does not designate 54.2*8.***.9 as permitted sender"

Is it our spam filter that is really blocking it? Or is it something on the sender's side? The reason I ask, is I have tried everything I can think of the get the mail to come through. Selected message and tried clicking "Deliver", "Whitelist", ect. I have whitelisted IP Address and allowed any email from that email address and or domain.

Answer 1

The problem you are describing is because the sender is not sending their emails through an authorized server. The fault is on their side! They have their SPF misconfigured. You can check their configuration using various SPF checking tools, such as MxToolbox or Kitterman.

In order fix this, you could either:

1. Contact their IT department and point them in the right direction for them to fix their problem
2. Disable SPF checks on your server (which I wouldn't recommend unless you want to be flooded with SPAM).