Why would this happen?
The Outlook Plug-in has a feature to allow users to compose emails offline, add ShareFile attachments, and send the message. These messages go to the Outbox but wait for Outlook to detect an active internet connection and be processed and sent.
In the case that the user closes Outlook before a connection is established, the plug-in has a feature that allows it to scan the Outbox at startup and ensure that any messages with ShareFile attachments are processed. Messages that aren't marked to be processed by the Plug-in are sent via Outlook's default method.
This is likely where the issue is. For some reason those old messages were not sent by Outlook and remained in the Outbox, until the ShareFile Plug-in was added to Outlook and sent the messages.
Our team will investigate this and make any necessary improvements. As a work-around, remove any old messages from the Outbox before installing the Plug-in to prevent them from being sent.
I apologize for the unintended behavior and hope this helps.
I would like to add to this thread. We are in the process of rolling out the Sharefile plugin to our users, and I have had two reports now of emails mysteriously being resent. While investigating, it was 3 messages for both users. the messages were over 7 days old. The email gateway shows proof the messages were resent. Outlook "Sent Items" only shows the older "Sent Items". No new entries for the ones that resent. Exchange logs show different Message ID's for the messages. In our case, all the resent message were sent outside our organization. While I can understand thinking the messages were stuck in the Outbox, but the messages clearly sent the first time. It's just they were sent a second time. For both users, they had had the plugin installed the same day or previous day and then logged in. Now if like you say, the Outlook plug is scanning something, could there be something else it is picking up other than Outbox? Since the messages clearly were sent origiginally, days ago.
I'm sorry to hear that those old messages were sent unintentionally. We've identified the cause of this behavior. At startup, the ShareFile plug-in scans the Outbox for unsent messages with the intent of uploading attachments and sending messages with ShareFile attachments. It then calls Outlook's native send method all messages in the Outbox, instead of just those containing ShareFile attachments. A fix for this will be included in the next release.
Until that version is released, please ensure there are no unsent items in the Outbox at the time the plug-in is installed and run for the first time.