The 'pickup' folder on the Exchange server is a useful tool for testing mail flow on your Exchange and testing the mail content itself if you are wishing to test an odd visual effect on an email signature.
To use this feature you need to identify the 'pickup folder' where the Exchange will pick this up from.
The default location is C:\Program Files\Microsoft\Exchange Server\TransportRoles, however, this can be different on different versions of exchange or if manually changed.
To confirm the location open the exchange management shell and use the below command:
Get-TransportServer | fl pickup*
With this location confirmed you can then place/create a file into that location with the .EML file type and exchange will attempt to process this as normal.
In its simplest form, the file needs the data for FROM, TO, SUBJECT and any test for the body.
An example is shown below:
You can also paste any mail body or HTML code etc to test anything specific.
With this created, move the file into the pickup folder.
The name of the file itself is not important, just the Extension.
Within 5-10 seconds the file will change to a .tmp file and will not be editable during this time and when completed the file will disappear.
The email should then be received as per the content of the EML file, allowing you to confirm the mail flow and any other issues that the mail should have experienced.