I'm going crazy on this one. Sending todistribution groupemail addressexternally gives "550 5.1.1 User unknown" on RCPT TO. Works fine internally. I know this is caused by having "Block messages sent to recipients not listed in the Global Address List" enabled in the Anti-spam tab on the ETS. I can uncheck the box and external mail goes to the DG without a problem. What I'm trying to figure out is why the DG isn't in the GAL that the ETS sees. All single users with mailboxes work fine.I know it's something stupid that I've overlooked since I never have been able to get this to work. I've tried creating a new Edge subscription after the DG was added, ran sync, ran test, no errors. I also unchecked "require that all senders are authenticated" in the message delivery restrictions for the DG on the hub. Hide group is not checked. If anyone has any hints, please let me know.

Hi, The Edge server query ADAM to check whether the recipient exists. Therefore, I suggest you firstly check whether the Distribution Group has been synced to ADAM by referring to following article: http://technet.microsoft.com/en-us/library/bb266939(EXCHG.80).aspx Note: You can use Get-DistributionGroup to replace the Get-User command in the above article. In addition, by default, the Distribution Group requires an authenticated sender. The inbound email is not able to authenticate to server. Therefore, I suggest you uncheck the option and force Edgesync again by using command Start-EdgeSynchronization. Then, please check the result. Mike