I have an agent that fires"After new mail has arrived." It has been working well for some time now, but after we upgraded our servers to 8.5.1 we seem to be experiencing a problem. The agent has some code to check for certain conditions, like having an attachment, and if the conditions are met, to forward the email to an outside vendor. After the upgrade the outside vendor said they got 2 of the emails twice. We tracked this down to an internal user forwarding the email to someone else within our company. It appears that the agent is firing when the “sent” email is being written to the database, or when the email is opened, edited, and closed, although I know it should not do this.
The act of simply forwarding an email (no editing of the original email is being done), causes the modification date on the original email to be updated, and triggers the “After new mail has arrived” agent to fire on the OLD email. What I’ve done in the past is to set a flag on all emails processed by the “After new mail has arrived” agent, and it looks like I’ll now have to add this flag to all OLD emails too.
It is not possible for the agent to processes “sent” mails (they don’t have the internal flags needed) or when mail is opened or closed (it does not look for client event). Editing the already delivered mail and thus changing the date it has been modified could cause re-processing (depending on the logic of your application). However, this is not a new behavior.
Another possible cause for multiple processing, is for someone to add an ini variable that stops ‘after mail delivery’ agent from working only on the home mail server of the user. This would cause the agent to run on multiple servers and could re-processes the same documents more than once.