This article is primarily written or shared as a best practices for getting started off while mail flow is stopped in Exchange Server 2010. Although the ideas shared in this blog can also help for other versions of Exchange Server.
To get started with it is advisable that one must know the basic understanding of Networking, DNS, Active Directory and other related technologies involved in sending and receiving of email.
In this blog we would be exploring some transport related issues and how to troubleshoot and fix it.
By default the logs are located in the following location.
C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\Connectivity.
Log format would look something similar to this.
When you are troubleshooting please understand the date when the issue occurred. The log will have the following format YYMMDD followed by a number.
Figure 1: Connectivity Log
In figure 1 the log clearly gives us a direction that there is a problem in SmarthostConnectorDelivery. Failed Connection to 10.0.1.10. MarkedUnhealthy | FailureCount: 1.
While looking at the logs there was a service which was marked as stopped and DC1 was acting as a SMTP server. Post starting the service the mail flow started.
Figure 2: Connection established
There are many other ways of troubleshooting mail flow issue. The above is just one example.