OK so I am using a hacky solution to this - basically I use a simple powershell script to change the FROM just before my mails go out.

I run this command:

powershell.exe -noexit -command "&{C:\ReportServer\ChangeFromEmail.ps1 -ConfigFilePath "C:\ReportServer\rsreportserver.config" -FromEmailAddress changetothis@myserver.ca}"

which runs to this script:

Param(

[string]$ConfigFilePath,

[string]$FromEmailAddress

)

Write-Host "Changing FROM Email to $FromEmailAddress"

[xml]$config = gc $ConfigFilePath

$config.SelectSingleNode("//From").InnerText = $FromEmailAddress;

$config.save($ConfigFilePath)

Then I change it back when I'm done using the same script, with different parameter.