I have had a VSTO add-in that has been out in the wild for some time. We have one client that reports that when he enters an email of someone that is out-of-office as a one of the recipients in a new email, that in the body of the email the out-of-office message for that person starts flashing in the body of the email. Of course, our add-in does nothing that relates to this. However, our client reports that if our add-in is uninstalled the flashing does not happen. We have had several people try to duplicate this anomaly (including our QA group), but are unable to duplicate. Does anybody have any suggestions? I have looked all over the web for something that might cause this flashing, but have not found anything. The client is using office 365 and currently I notice that the flashing appears to becoming from people in the same domain. I have asked him to use another account that is not in his domain and see if he can duplicate. In the mean time, is there any event or something in the Outlook object model that might give me more information. Thanks for any suggestions.
New Data I met with the client this morning and the symptom has changed with the new install I just sent him. Now the out-of-office is not displayed at all now. I added new logging information, and that was about it. I am starting to think that my add-in is causing the issue with querying the recipients. I am handling the Property Change event (to, cc, bcc) and creating a list of SMTP addresses for internal logic. I am starting to think I am querying the recipients too fast for Outlook. So I am going to create an event and slow the process down. This client has a user base of well over 500. What is strange is that we have a couple of clients with a much larger user base that do not show this issue.
