@mspmanager
So, if I understand the issue correctly, the Flow starts running within a few minutes or less of when the Form is submitted. Then, the Flow runs in about 10 seconds. The issue is that the recipient does not receive the email for up to an Hour.
It sounds like the issue may be on the exchange side.
Are you experiencing other email issues?
Do you have a copy of the email that was sent? If so, what is the time stamp on the email? Is it delayed or is it close to when the Flow completed?
Is this an issue with more than 1 user?
If you manually compose and send an email to one of the impacted users, do they receive the email in a timely fashion?