In our usecase, the automation is triggered by the arrival of a new mail. So, If we have 2 or more mails coming in at the same time, they are queued using StartActivity method. I have observed that while sending/receiving mails, at times Outlook gets stuck at "Preparing to Send/Receive" & "Updating Inbox". However, this happens only when outlook receives more than 3 mails at a time. For less than 3 mails it works smoothly.