Hi,

I am trying to use the setInReplyTo option in single email message to solve a conversation threading problem. I am querying for an emailmessage and then setting that Id as value for the method. I am encountering run time errors with this

System.EmailException: SendEmail failed. First exception on row 0; first error: INVALID_MESSAGE_ID_REFERENCE, In-Reply-To header is not valid.: []

I am not sure how to set this up to work. Please help.

Thanks

KD