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Lots of Email sent to postmaster@mydomain.com from "MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@mydomain.com"

Question

Monday, October 28, 2019 10:48 AM

Dear All,

I have issue with this ID "MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@mydomain.com" and per day 50 email sent from this id to postmaster@mydomain.com and i tried to create rule on-premise exchange server as well as from exchange online to stop sending email to postmaster@mydomain.com but still i can see email sent to postmaster@mydomain.com in the Mimecast and since we are running Hybrid environment.

And i don't find this mailbox related to this from my on-premise exchange server "MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@mydomain.com"

I would appreciate response on this issue.

Warm Regards,

Saroop

All replies (8)

Monday, October 28, 2019 5:16 PM

Hi.

It's service account Microsoft Exchange. 

Open ADSIEDIT – Configuration

Services -> Microsoft Exchange -> 'Name your Exchange Organization” -> Transport Settings -> CN=MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e

MCITP, MCSE. Regards, Oleg


Tuesday, October 29, 2019 7:53 AM

Thanks for your reply and i know this and i wanted to know and why it is sending email to postmaster@mydomain.com and this ID in Mimecast cloud and as per my Transport rule should block sending email to but still sending.


Tuesday, October 29, 2019 7:56 AM

Are they NDR messages or warning messages saying that "your mailbox size hits the quota"? Could you kindly post the entire message here?

It seems that system-generated messages or notifications fail to deliver to the message senders that exist outside of your organization. Then the service account generates a bounce message to your postmaster address.

Configure the external postmaster address

To further confirm this, please run command below to see if any message got stuck in your transport queue of on-premises Exchange server.

Get-Queue | Get-Message | fl 

Regards,

Manu Meng

Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


Tuesday, October 29, 2019 8:02 AM

Hi Manu,

This command is not working and i checked with Mimecast and they said this email is generating from our on-premise exchange server and i have the header i can share with you, do you mind if i have you email and sent to you.

Saroop


Tuesday, October 29, 2019 8:08 AM

i can see in header and received from our server our (Public IP) and subject is 

Subject Undeliverable: You have new held messages

Tuesday, October 29, 2019 8:18 AM

I don't see NDR related to any mailbox like you said mailbox size etc and it said in header "Subject Undeliverable: You have new held messages" 


Wednesday, October 30, 2019 8:22 AM

Hi Manu,

This command is not working and i checked with Mimecast and they said this email is generating from our on-premise exchange server and i have the header i can share with you, do you mind if i have you email and sent to you.

Saroop

What do you mean by "the command is not working"? You got an empty result or encountered errors?

Sorry but it is not compliant to contact our customers through emails, you should remove the sensitive info before finally sending your reply.

Regards,

Manu Meng

Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


Wednesday, October 30, 2019 8:57 AM

Hello

Create Domain Spoof Prevention rules 

Name  Domain Spoof Prevention

Apply this rule if..
   The Sender is located      OutSide the Organization

and
The Sender's domain is       "Your Domain"

Do The Following ...
reject /delete

Except if...
Sender's IP address is in the range   "Your IP"

Regards

Bhupen