Question: We are receiving an SMTP 4.4.1 connection time out exception every so often when attempting to send mail in C#. So far we have found no pattern as to when the issue occurs, such as the time of day. 

The exception thrown is:

> 
> System.Net.Mail.SmtpException: Service not available, closing transmission channel. The server response was: 4.4.1 Connection timed out
> 
> 
> 

Up to 30 emails at anyone time are sent and 9 times out of 10 all are sent successfully. When we run into the 4.4.1 exception a number of the emails are sent and the remaining 1 or 2 are not. 

Unfortunately, I don't have access to the clients Exchange server, only the application server where our application is running from. So I'm working with the host on this. The Event Log has been checked on the application server, the only thing found was the following warning from a source McLogEvent:

> 
> Would be blocked by port blocking rule (rule is in warn-only mode) (Anti-virus Standard Protection: Prevent mass mailing worms from sending mail).
> 
> 
> 

Has anyone came across this issue before or know of a possible cause?

Answer: 
You must use a major upgrade if you remove components. See [Changing the Product Code](https://msdn.microsoft.com/en-us/library/aa367850%28v=vs.85%29.aspx) for the list of things that cannot be done with minor upgrades.
@Bob Arnson: I don't want to do a major upgrade as I want the previous version to be not uninstalled but upgraded. So I came up with a fix for now using RemoveFile tag under those components that specifies those file ids to be deleted in case they are present.

```
<RemoveFile Id = "id_to_be_removed" On = "uninstall" Name = "dll_name"/>

```