It is always best to perform a test via telnet to insure that mail flow is functional through ProofPoint Essentials to your Azure Tenant. Below are some simple steps to insure mail flow is functional.
1- Launch a command prompt in windows by click the WINDOWS key and type CMD then ENTER.
2- To test email flow you need to send a test email to an existing synced account in Azure. as was done in STEP 2.
3- From the command prompt perform a telnet to connect to ProofPoint Essentials MX records, depending on which stack you may need to telnet to the European stack or the US stack, these are two different MX records as shown in step 4.
4- Type the following command in a command prompt and hit ENTER.
5- You should be greeted with the following SMTP banner.
6- Now you can enter the telnet strings that will allow you to test mail flow.
7- Type the following commands as highlighted with arrows on the screen below and then press ENTER. Each time you press ENTER, a return response will show up. Be sure that
the MAIL FROM address is a public email address not found on ProofPoint Essentials.
8- The final line that indicates queued as 7070E40006C means that ProofPoint Essentials has received your email and is processing it.
9- You may now verify with the inbound logs of ProofPoint Essentials if the email was received and delivered.
10- To access the logs in ProofPoint Essentials click on Log Search and enter the options Inbound - Any and select the date and press Search.
11- A success full result with be indicated as listed below in the Log Search.
12- This result indicates a successful mail delivery and your domain is ready to go live.
13- You can now proceed to STEP 5 - MX Record and Outbound Relay