Trying to create a new SQL Server 2005 Reporting Services subscription and keep getting the following error:-

Failure sending mail: At least one of the From or Sender fields is required, and neither was found.

I've checked and the To and Reply-To fields have a full email extension e.g. MyName@Company.com

The fix is quite an easy one:-

Look in the RSReportServer.config file usual located in:-

C:\Program Files\Microsoft SQL Server\MSSQL.1\Reporting Services\ReportServer

Search under the <RSEmailDPConfiguration> for <From></From> here I noticed it had the server name so <From>ReportServer1</From>. 

I changed this to be <From>Support@Company.com</From> and now the subscription works fine.