How to start
I have been approached many times by users claiming that they never received a particular Email message. So where does one start looking? Most of the following scenarios have happened to me. The rest are follow-up thoughts of my own.
I start by asking my user some questions:
- What was the sending address?
- Approximately what time was the message sent?
- Are you seeing other messages arrive?
- If necessary may I open your mailbox to investigate?
I could also ask if the sender received a "bounce" message (a.k.a. Non-Delivery Report, a.k.a. NDR), but that tends to take extra coordinative effort. It's easier to assume that the sender is fine and to search for issues in the environment you can control (i.e. your own). Prove your own system sound before trying to look for causes outside. Show that you want to solve problems and not look for someone to blame.
Armed with this information, let's consider some possibilities:
1. It never reached our systems
2. It reached our systems but did not reach Exchange
3. It reached Exchange but was not delivered to the recipient's mailbox
4. It reached the recipient's mailbox but does not appear in the client software
The list is sorted according to message flow, but that does not mean you have to investigate in the same order.
The first question I ask myself is, does Exchange think it was delivered to the recipient's mailbox? Most of the time I find that the message did in fact reach the recipient's mailbox and something was done to it either automatically or manually.
Use Message Tracking (MT) to confirm whether the message was delivered. Use the information obtained from the user as the search parameters. If MT finds the message (regardless of outcome), rule out #1 and #2. If MT reports "Message delivered locally to store", it reached the recipient ruling out #3.
At this point, let's break the investigation into three parts.
If you cannot find the message in MT, continue with Part 2, Message Tracking does not find the message I was expecting, where could it be?
If MT finds the message, but reports something other than "delivered locally", continue with Part 3, Message Tracking sees the message, but it was not delivered to the mailbox
If MT does not find the message, continue with Part 4, The message was delivered to the mailbox - where did it go?