The importance of email auditing

Imagine a scenario where the customer uses Microsoft's Exchange Online service, among other robust email control and auditing tools, it allows you to check if an email actually reached the recipient's server or if it was actually sent by the sender.

How Sending Email Works

To continue, it is important to understand the following definitions:

  • Email or user account: is what comes before @.
  • Domain: is what comes after @.
  • Email address: email account + domain.
  • Example: the email address [email protected] is made up of the email account “contact” plus the domain “”.
  • Email sending process: see the image below.

Imagine that we audited our client's email account looking for emails sent on a specific date, first we identified that the email had been delivered to the server responsible for the email service in the recipient's domain, then we audited the emails received by our client's account, in order to search for any notice that he has received but did not notice, we have not found any warning email about incorrect address.

Read more:
Exchange Online vs. Exchange Server: What is more worth today?
PST email backup via Powershell
Receiving error after Mailbox restore

It is important to understand that in the process of sending emails, the sender is able to audit the process until the email is delivered to the recipient's server, verify that the email was delivered to the recipient's account is the responsibility of the recipient's email server, only those manages that server can confirm delivery to the recipient's email account.

Any error message when sending to an email account (for example incorrect or full / no available space), always leaves the server responsible for the recipient's email, only if the domain is incorrect will the sender's server be able to issue a warning .

In this case, a warning that the recipient's address was incorrect (correct domain but incorrect email account), should come from the recipient's server, so if there was no error warning this should be checked with the IT team responsible for the emails recipient.

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In case of doubts or problems in the execution, you can leave your comment and we will reply soon.

Thank you and see you in the next post.

Felipe Santos
Felipe Santos is a Cloud and Security Architect, with experience in Windows Server, Cluster, Storages, Backups Veeam and Office 365 environments.



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