I was helping a client server as mentioned the email form could send an email.
The server ran with IIS 7.5 with IIS SMTP services. Hence, I was trying to open the IIS 6.0 and start the SMTP services when found it is stopped.
At the same time, the event viewer is showing the error as below.
Event ID: 115 Source: SMTPSVC Description: The service could not bind instance 1. The data is the error code.
With the above error, it might meant that the SMTP port of 25 is being assigned to your email software installed to the server. To overcome the problem, refer to the step as below.
1. Open the IIS 6.0.
2. Double click the hostname and right click the Default SMTP Virtual Server then click on Properties.
3. Click on the Advance button and change the TCP port to 2525.
Well done, you have done.