Directories - Alias Email Addresses

This article contains information on how Mimecast applies policies to primary and alias email addresses, linking aliases to primary accounts, managing alias associations, and considerations for archive access and directory synchronization changes.

Typically users are set up with one primary email address, but some organizations will also create proxy or alias addresses. An alias email address is an additional address that can be used to contact an end user and doesn't have to be in the same domain as their primary account. For example, companies that merge may have end users with primary and alias addresses in different domains, or require clients to contact them on different email addresses.

Generally speaking, these addresses are redirected at the mail server level to the primary account. This enables their email client to receive all messages sent to either the primary or alias email address. 

How Mimecast policies are applied to primary and alias addresses

When an email is received, the recipient address is checked to see if it is an alias or a primary address.  If it is an alias, it is resolved to the primary address, and policies are applied. All policy scoping is based on the primary address.

Using Alias Email Addresses

We create personal email archives based on email addresses. It is important to link these addresses. This ensures that when a user logs onto their primary email address, recent messages sent to an alias email address are also seen.

Linking alias addresses to the primary address can be done in several ways:

• • Automatically: We can automatically link your alias addresses to their primary address using the information gathered via your Directory Connection. When enabled, we automatically link the alias addresses found in your network controller, to the user's primary addresses on the next Directory Synchronization. See the "Directory Options" section of the Email Security Cloud Gateway - Mimecast Account Settings page for further details.
  • Spreadsheet Import: For alias addresses in the same domain and across domains, a spreadsheet import can be used. See Email Security Cloud Gateway - Spreadsheet Import for further details.
  • Manually: You can also link multiple alias email addresses to a primary email address, as long as they are in the same domain. See the Email Security Cloud Gateway - Managing User Email Addresses page for further details.

Administrators can unlink aliases associated with a primary address, making the aliases act as primary addresses. If the alias information was provided to Mimecast via a Directory Synchronization, and the Directory source hasn’t been updated, the alias link will be re-established when the directory next synchronizes.
Additionally, administrators can manually create an alias association.

Considerations

• • If there is a requirement for one account to have access to multiple archives (e.g. because of a name change) administrators with sufficient privileges can assign multiple archives to a primary address using delegate mailbox access. See the Email Security Cloud Gateway - Configuring Delegate Mailbox Access page for further details.
  • When a user's primary SMTP email address is changed, the address displayed in the user's profile in Microsoft Outlook doesn't change. For example, if a user's primary SMTP email address is [e-mail], but their primary SMTP email address is changed to [e-mail], the primary SMTP email address displayed in Outlook remains as [e-mail]. This is by design, as the email address in the root folder is determined at the time of profile creation, and does not reflect the primary SMTP address stamped on the user. To work around this issue, delete and re-create the user profile.

Unlinking of Alias Addresses

If changes occur in your directory structure, we must reflect any changes to the alias records during each synchronization. For example, if:

• • A primary email address is removed as part of a synchronization, any aliases must be unlinked.
  • The alias is moved to another primary address, it must be re-linked to the new address.
  • An alias becomes a primary address, any prior links should be removed.