We would like to enable one external vendor the ability to email our internal Everyone distribution list. Currently we have the DL restricted to only people inside our organization. We want to continue with this restriction

What options do we have to allow anyone in the company to send to this DL, while maintaining only one external email sender? I tried creating a contact in our GAL for the external party, but still get a bounce back about not being authenticated (which makes sense). Would a hub transport rule and no restriction on the DL be the best option?

Bounce Back Message received

Remote Server returned '550 5.7.1 RESOLVER.RST.AuthRequired; authentication
required'

Thanks

We would like to enable one external vendor the ability to email our internal Everyone distribution list. Currently we have the DL restricted to only people inside our organization. We want to continue with this restriction

What options do we have to allow anyone in the company to send to this DL, while maintaining only one external email sender? I tried creating a contact in our GAL for the external party, but still get a bounce back about not being authenticated (which makes sense). Would a hub transport rule and no restriction on the DL be the best option?

Bounce Back Message received

Remote Server returned '550 5.7.1 RESOLVER.RST.AuthRequired; authentication
required'

Thanks

I would use a transport rule, yes.

So remove the authenticated user requirement, then have the rule say, if from the outside, delete/block the message to that DL except from the external sender's SMTP address.