Public folder - (mail enable) reject mails from outside of organization

%3CLINGO-SUB%20id%3D%22lingo-sub-1945897%22%20slang%3D%22en-US%22%3EPublic%20folder%20-%20(mail%20enable)%20reject%20mails%20from%20outside%20of%20organization%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-1945897%22%20slang%3D%22en-US%22%3E%3CP%3EHi%2C%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3Ecreated%20public%20folder%20-%20set%20mail%20enable%20to%20it%3C%2FP%3E%3CP%3ESMTP%20(primary)%3A%20%3CA%20href%3D%22mailto%3AXXX%40domainname.onmicrosoft.com%22%20target%3D%22_blank%22%20rel%3D%22nofollow%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%20noopener%20noreferrer%22%3EXXX%40domainname.onmicrosoft.com%3C%2FA%3E%3C%2FP%3E%3CP%3ESMTP%3A%20XXX%40domainname%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3Eset%20Public%20Folder%20permission%20(from%20my%20outlook%202013)%20anonymous%20create%20items%2F%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3Ewhen%20sending%20test%20message%20from%20GMAIL%20to%20this%20SMTP%20-%20public%20folder%20-%20the%20message%20is%20reject%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3Ethis%20is%20the%20error%20I'm%20getting%3A%26nbsp%3B%3C%2FP%3E%3CP%3E%3CSTRONG%3EAM5EUR02FT046.mail.protection.outlook.com%20gave%20this%20error%3A%3CBR%20%2F%3ERecipient%20address%20rejected%3A%20Access%20denied.%20AS(201806281)%20%5BAM5EUR02FT046.eop-EUR02.prod.protection.outlook.com%5D%3CBR%20%2F%3E%3C%2FSTRONG%3E%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3Ehow%20to%20fix%20it%3F%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EThankgs%3C%2FP%3E%3C%2FLINGO-BODY%3E%3CLINGO-LABS%20id%3D%22lingo-labs-1945897%22%20slang%3D%22en-US%22%3E%3CLINGO-LABEL%3EOffice%20365%3C%2FLINGO-LABEL%3E%3C%2FLINGO-LABS%3E%3CLINGO-SUB%20id%3D%22lingo-sub-1947543%22%20slang%3D%22en-US%22%3ERe%3A%20Public%20folder%20-%20(mail%20enable)%20reject%20mails%20from%20outside%20of%20organization%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-1947543%22%20slang%3D%22en-US%22%3E%3CP%3EThat's%20the%20expected%20behavior%2C%20sort%20of.%20Exchange%20Online%20utilizes%20a%20feature%20called%20DBEB%2C%20which%20blocks%20messages%20sent%20to%20%22unknown%22%20recipients.%20This%20feature%20doesnt%20support%20cloud%20PFs%2C%20so%20any%20external%20email%20sent%20to%20them%20will%20be%20rejected.%20The%20workaround%20is%20to%20%22disable%22%20this%20feature%20by%20changing%20the%20domain%20to%20%22Internal%20relay%22.%20Or%20sync%20PFs%20from%20on-premises.%20Details%20are%20here%3A%26nbsp%3B%3CA%20href%3D%22https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fexchange%2Fmail-flow-best-practices%2Fuse-directory-based-edge-blocking%22%20target%3D%22_blank%22%20rel%3D%22noopener%20noreferrer%20noopener%20noreferrer%22%3Ehttps%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fexchange%2Fmail-flow-best-practices%2Fuse-directory-based-edge-blocking%3C%2FA%3E%3C%2FP%3E%3C%2FLINGO-BODY%3E
Contributor

Hi,

 

created public folder - set mail enable to it

SMTP (primary): XXX@domainname.onmicrosoft.com

SMTP: XXX@domainname

 

set Public Folder permission (from my outlook 2013) anonymous create items/

 

when sending test message from GMAIL to this SMTP - public folder - the message is reject

 

this is the error I'm getting: 

AM5EUR02FT046.mail.protection.outlook.com gave this error:
Recipient address rejected: Access denied. AS(201806281) [AM5EUR02FT046.eop-EUR02.prod.protection.outlook.com]

 

how to fix it?

 

Thankgs

1 Reply

That's the expected behavior, sort of. Exchange Online utilizes a feature called DBEB, which blocks messages sent to "unknown" recipients. This feature doesnt support cloud PFs, so any external email sent to them will be rejected. The workaround is to "disable" this feature by changing the domain to "Internal relay". Or sync PFs from on-premises. Details are here: https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-directory-based-edge-blocking