We have a web based on-send Outlook add-in (not Smart Alerts) that works well.
Our client uses Proofpoint, an Outlook COM add-in that appends "[secure]" into the subject of the outgoing email under certain circumstances (like if there's an attachment).
The two add-ins work fine separately, but when used together, the Proofpoint COM add-in fails to insert the "[secure]" keyword into the subject of the outgoing email. Our web based on-send add-in is called normally.
How can we diagnose what is going wrong? Is there a defined order for which add-ins run when (for example, do all COM Add-Ins always run first)? Can multiple add-ins both make modifications to the outgoing email?