So the complaint is (and it's not very hard to spell this out so we don't have to play your guessing games): after delivering the message, the PR_ATTACH_LONG_PATHNAME property is missing/blank.
Why would you expect to see a pathname on a delivered message? The PATHNAME properties are used in creating an attachment, where MAPI and the store provider need to know where on disk to get the data for attachment. Once a mail is in transit and ultimately delivered, the attachment only exists on the message. PATHNAME makes no sense to be set at that point.
Why would you expect to see a pathname on a delivered message? The PATHNAME properties are used in creating an attachment, where MAPI and the store provider need to know where on disk to get the data for attachment. Once a mail is in transit and ultimately delivered, the attachment only exists on the message. PATHNAME makes no sense to be set at that point.