I have had a problem the last 4 weeks as some clients are not receiving our emails. I have been checking our logs and they are leaving our exchange server correctly, but the clients are not receiving the emails. I am not receiving any NDR reports. I have not made any changes our our Exchange 2003 server. Does anyone have any other ideas on what I can check. Thanks GregGreg Smith

If they are being sent out and no NDR then either they are lost along the route or they are being received. Ask them to check their end at the gateway or Exch MT logs. If their end shows Exch received then it's down to their side.Sukh

Hi, I agree with Sukh. Besides, please verify if the issue only occur to certain external domain or certain external recipient.Xiu Zhang TechNet Community Support

Any update?Xiu Zhang TechNet Community Support

Well, I found out that Comcast was filtering us because we had a phone number in our signature in outlook. They are going to remove the filter. I wish somehow if someone is filtering us that we would get some type of error message so we know this is happening. I having a feeling that larger internet providers are doing a lot more filtering. Is there a better way to get around filtering? Thanks GregGreg Smith

Well, I found out that Comcast was filtering us because we had a phone number in our signature in outlook. They are going to remove the filter. I wish somehow if someone is filtering us that we would get some type of error message so we know this is happening. I having a feeling that larger internet providers are doing a lot more filtering. Is there a better way to get around filtering? Thanks Greg Greg Smith Not really, each ISP may use different filters/subscriptions.Sukh