Approved and Blocked Senders Lists

An Approved Senders list is a list of trusted email addresses. The Messaging Security Agent does not filter messages arriving from these addresses for spam except when Detect Phishing incidents is enabled. When you have enabled Detect Phishing incidents, and the agent detects a phishing incident in an email, then that email message will not be delivered even when it belongs to an approved sender list. A Blocked Senders list is a list of suspect email addresses. The agent always categorizes email messages from blocked senders as spam and takes the appropriate action.

There are two Approved Senders lists: one for the Microsoft Exchange Administrator and one for the end-users.

  • The Microsoft Exchange Administrator’s Approved Senders list and Blocked Senders list (on the Anti-spam screen) control how the Messaging Security Agent handles email messages bound for the Microsoft Exchange server.

  • The end-user manages the Spam Folder that is created for them during installation. The end-users’ lists only affect the messages bound for the server-side mailbox store for each individual end-user.

General Guidelines

  • Approved and Blocked Senders lists on a Microsoft Exchange server override the Approved and Blocked Senders lists on a client. For example, the sender “” is on the Administrator’s Blocked Senders list, but the end-user has added that address to his Approved Senders list. Messages from that sender arrive at the Microsoft Exchange store and the Messaging Security Agent detects them as spam and takes action against them. If the agent takes the Quarantine message to user’s spam folder action, it will attempt to deliver the message to the end user’s Spam folder, but the message will be redirected to the end user’s inbox instead because the end user has approved that sender.

  • When you are using Outlook, there is a size limit for the amount and size of addresses on the list. To prevent a system error, the Messaging Security Agent limits the amount of addresses that an end user can include in his or her approved sender list (this limit is calculated according to the length and the number of email addresses).

Wildcard Matching

The Messaging Security Agent supports wildcard matching for Approved and Blocked Senders lists. It uses the asterisk (*) as the wildcard character.

The Messaging Security Agent does not support the wildcard match on the user name part. However, if you type a pattern such as “*”, the agent still treats it as “”.

You can only use a wildcard if it is:

  • Next to only one period and the first or last character of a string

  • To the left of an @ sign and the first character in the string

  • Any missing section at the beginning or end of the string serves the same function as a wildcard

Table 1. Email Address Matches for Wildcards


Matched Samples

Unmatched Samples

Any address different from the pattern








The same as “*”




Invalid patterns