Error sending custom E-mails

Jan 12, 2011 at 5:26 PM

Hello,

I keep getting this error message with any of the custom E-Mail actions:

System.NullReferenceException: Object reference not set to an instance of an object.
   at DP.Sharepoint.Workflow.Common.SendMailWithAttachment(SPSite site, String from, String to, String cc, String subject, String body, AttachmentInfo[] attachments, Boo

The outgoing E-Mail settings in Central Administration and the values in SPD are all set. Coincidentally, the E-Mail actions are working on a similar system with an earlier SharePoint build number. Does anybody have an idea how to solve this problem?