Policies - Address Alteration Configuration

This article contains information on configuring Address Alteration policies in Mimecast, including creating definitions, modifying email addresses for specific traffic routes, and managing policies for inbound and outbound messages.

An Address Alterations policy modifies the email address to which inbound or outbound messages are sent as they are processed for delivery. For example:

• A merger requires all messages to the acquired company to be sent to the acquiring company's domain.
• Your organization needs to modify address information based on mail flow (e.g., inbound messages destined for [e-mail] should be delivered to [e-mail].
• Any sender from a Support Desk group sending an outbound email needs the 'From' address to appear as if it's sent from the [e-mail] group address.

Address Alteration Definitions

Consider the following before creating a definition:

• Address Alteration definitions can be created in any folder, including the root folder. This determines if a policy is required:

Folder	Comments
Root Folder	No policy is required. Anytime a match is found, the address is rewritten.
Sub Folder	Create a definition if you only want specific addresses to be amended in certain traffic flows. In this instance, an Address Alteration policy must be configured to specify when the Address Alteration applies.

• The destination server must be configured to accept inbound emails with altered addresses.
• If a re-written address email cannot be delivered to the next hop mail server, the postmaster sends the Non-Delivery Report (NDR) to the new re-written address (not the original address).
• Address rewrites can support the concept of specificity. For example, within a rewritten set, 'one-to-one' email addresses take preference over local part policies, taking priority over domain-level rewrites.
• When searching the archive, you must search for the address specified in the Address Alteration definition's New Address field. The search is unable to find the Old Address.
• Should you require that outbound messages be rewritten to a domain not registered to your account, the domain owner must add the DNS Authorization code in your Account Settings to allow messages to pass SPF checks.
• Emails redirected to a new address with no public MX record will not be delivered. 

Configuring Individual Address Alteration Definitions

1. Log in to the Mimecast Administration Console.
2. Navigate to Policies | Gateway Policies | Address Alterations (Definitions button).
3. Click on either of the following:

• • Definition to be changed.
  • New Address Alteration button to create a definition. If the New Address contains an external domain, the following warning message appears:
    
     

 

4. Click OK. This makes a new audit log entry.
5. Complete the Address Alteration Properties as follows:

   An asterisk (*) can be used in the Original Address and New Address fields to substitute email address information. For example, if *@domain.com is entered in the Original Address field, all the company's email addresses will be altered to the value specified in the New Address field.

Field / Option	Description
Original Address	Enter the original email address.
New Address	Enter the new email address.
Applied Route	Specifies the route for Inbound, Outbound, or Inbound and Outbound messages.
Address Type	Specify what address type is to be altered. The options are: Applies to All Addresses: All header and envelope addresses are modified. Envelope FROM Address: Only the primary sender's SMTP address is changed. Envelope TO Address: Only the primary recipient's SMTP address is changed. Header [From] Address: Only the main sender header address is changed. Header [Reply-To] Address: Only the reply to the header address is modified. This can be used where address details must not be changed unless the recipient chooses to reply to a message. In this instance, the message can be sent to a different email address/domain. Header [To/CC/Bcc] Address(es): The header addresses in any To, CC, or BCC fields are modified. Header [Sender] Address: The header address in the sender field is modified.

6. Click on the Save and Exit button.

Configuring Multiple Address Alteration Definitions

To configure multiple Address Alteration definitions:

1. Follow Steps 1-5 in the "Configuring One Address Alteration Definition" section above.
2. Click on the Build button.
3. Click on the Bulk Addition menu item.
4. Add each definition's detail on a separate line using the following format:

Field	Description	Values Allowed	Comments
1	Routing	all inbound outbound	The "all" value allows you to specify both inbound and outbound traffic.
2	Address Type	all [from] [to] from to reply	The "all" value allows you to create a re-write entry that works on all addresses regardless of envelope or header. The [] brackets indicate the envelope FROM rather than the header FROM. No brackets indicate the header address.
3	Old Address	localpart@domainpart *@domainpart localpart@*
4	New Address	localpart@domainpart *@domainpart localpart@*

5. Click on the Save and Exit button.

   Creating a Microsoft Excel file with no header row and four columns may be more manageable. Instead, export the file in a tab-delimited (.TXT) format and copy/paste the content into the text box in Step 4. While simple spaces between columns are accepted, double quotes are not.

Configuring Address Alteration Policies

Consider the following before creating a policy:

• Address Alteration policies must only be used if the address alterations are required for specific traffic routes.
• If the Address Alteration is specifically for the recipient, the message is delivered only to the new rewritten address.
• We cannot affect internal emails routed within an organization's infrastructure as a cloud service.
• Each policy is created based on the following:
  • Header (sender or recipient) email address.
  • Envelope email address information.

To configure an Address Alteration policy:

1. Log in to the Mimecast Administration Console.
2. Navigate to Policies | Gateway Policies | Address Alterations menu item.
3. Either select the:

• • Policy to be changed.
  • New Policy button to create a policy.

4.   Complete the Options section as required:

Field / Option	Description
Policy Narrative	Describe the policy to allow you to identify it quickly and easily in the future.
Select Address Alteration Set	Use the Lookup button to select the required Address Alteration definition for the policy.

5. Complete the remainder of the policy as necessary; refer to the Policy Basics KB article if needed.
6. Click on the Save and Exit button.

See Also...

• • • Address Alteration Bypass