Hi folks; I have a exchange 2007 enviroment.There are lots of mail enabled distribution and security groups.But sometimes when a user sent a message to group, no groupmember were able to recieve this mesage.But no ndr message appears. If i go to the queue viewer i dont see this message but there are loop messages.If i delete this messages from queue ,users can send message to the group. No warning no error message on event viewer and no ndr message.Just disapparing. Where should i check to diagnose this problem?

Please make sure that they are not sending mail to "Securtiy group" because security group use to apply permission while "Distribution group" apply for permission and emailing

I migrated all groups with admt.They were not mail-enabled and manually i mail-enabled them.Is this a problem?

Hi Without knowing a lot about your environment I would think this is a loop or routing issue.. Please give us all information about the mailflow, in and outgoing in detailJonas Andersson MCTS: Microsoft Exchange Server 2007/2010 | MCITP: EMA 2007/2010 | MCSE/MCSA Blog: http://www.testlabs.se/blog

Hi, Does the problem happen in more than one groups? Is the message from a internal user? Please check if the "RequireSenderAuthentication" is enabled on the group: 1. Open Exchange Management Shell, type: get-Distributiongroup GroupAlias|fl 2. If the "RequireSenderAuthenticationEnable" is true, please run the following command to disable it: Set-Distributiongroup Distributiongroup –RequireSenderAuthentication Enable:$false If SenderAuthentication is already disabled, please run message tracking tool to track this message: 1. Open EMS, click Toolbox, open Message Tracking. 2. Specify the sender, server ,start time and end time, uncheck the EventID and click Next. 3. Click MessageSubject to sort the list. Locate the disappeared message. What's result? Does the log indicate the message has been delivered to the all recipients? Do you see any 'FAIL' events?

In our environment there are 2 exchange forest.A cross forest migration project is in process. Each exchange has internal relay connectors for same smtp namespace and during migration for all users,coexistance scenario will be used.If a user has been migrated , and he send a mail to this group all users from this domain and all contacts from cross domain will recieve this message. But sometimes it doesnt't work.no ndr. All groups migrated and they are security mailenabled groups.Is there RequireSenderAuthentication attribute for security groups? will look also message tracking

All groups migrated and they are security mailenabled groups.Is there RequireSenderAuthentication attribute for security groups? will look also message tracking RequireSenderAuthenticationEnabled is an exchange recipient property, so all exchange distribution groups hold it. use this command to disable this flag: Set-Distributiongroup DGEmailID –RequireSenderAuthentication Enabled $false Regards,Laeeq Qazi|Team Lead(Exchange + Sharepoint + BES + DynamicsCRM) www.HostingController.com