What is SMTP Discovery?

SMTP Discovery, as part of the Advanced Email Security add-on, monitors email addresses that are sent mail using your domain name, but aren’t already added as users or functional accounts in Proofpoint.

If you receive an SMTP Discovery Warning Report from Proofpoint, you’ll be informed in the email whether you need to add the address to your organization as a distribution list, end user address, or alias. Otherwise, you can mark it as an invalid account.

Warning: If no action is taken within 4 weeks of receiving the report, it could impact mail flow for the affected email addresses.

Add a distribution list

You can add the address to an existing distribution list.

1. Sign in to Advanced Email Security.
2. Under Administration, select User Management > SMTP Discovery.
3. Select the check box next to the distribution list address you want to add.
4. Select Create functional account. It can take up to 90 minutes for these changes to take effect.

Add an end user address

You’ll want to add a user when the email address is part of your Microsoft 365 account but hasn’t been added in Advanced Email Security yet.

1. Sign in to Advanced Email Security.
2. Under Administration, select User Management > SMTP Discovery.
3. Select the discovered address you’d like to add.
4. Enter the FIRSTNAME and SURNAME.
5. Select Create user account from the list, and then Apply.

Add an alias

When there’s already an existing user in Advanced Email Security, you can add an alias. This should be the same email alias that’s in your Microsoft 365 account.

1. Sign in to Advanced Email Security.
2. Under Administration, select User Management > SMTP Discovery.
3. Select the discovered address you’d like to add.
4. Under OR Add as Alias, enter an existing user’s email address for the alias.
5. Select Apply.

Mark as an invalid account

Identify a discovered address as invalid so mail isn’t delivered to it.

1. Sign in to Advanced Email Security.
2. Under Administration , select User Management > SMTP Discovery.
3. Select the discovered address you’d like to identify as invalid.
4. Select Mark as Invalid Account, and then Apply.

More info

• SMTP Discovery runs 4 times a day, so there may be a delay in discovered addresses appearing.
• Send encrypted email using Advanced Email Security.
• Here are ways you can customize Advanced Email Security.