Mimecast for Outlook

Mimecast for Outlook provides the means for user to manage their Mimecast data from within Outlook itself. This includes management of Archive data, Hold Queues (Personal and Moderated) & Blocked/Permitted Senders. If you have additional Mimecast services, such as Continuity or Secure Messaging, Mimecast for Outlook can also be used to interact with these.

Before using the Mimecast for Outlook app, it must be enabled by your Mimecast Administrator.


In some cases, Mimecast for Outlook may automatically log you into your account. Should it require a manual sign-in, you will see a prompt like the below:

Clicking on this prompt will take you to the sign-in screen. The steps below cover navigating to the sign-in screen should this not appear or if it was closed.

  1. Select the Mimecast ribbon
  2. Select Account Settings

  1. Select Authenticate next to the relevant Authentication Option
    1. If you aren’t sure which option to use, check with your Mimecast Administrator

  1. Enter the login for your Mimecast account
  2. Press Submit Password

Note: This screen may be different if your Mimecast Admin has set different options

Search the Archive

If your Mimecast account is enabled for Archiving, you can use the Mimecast for Outlook plugin to search for previous messages that have been captured. From this, you can restore messages that may have been deleted in the past.

The Mimecast for Outlook plugin only searches the archive for the account you are logged in with. If you need to perform a search across your organisation, you should perform the search in the Administration Console.

If you don’t see the Search options, this service may have been disabled by your Mimecast Administrator.

  1. Select the Mimecast ribbon
  2. Select Search

  1. Enter the criteria for your search
    1. You can use the Search Options icon in the search bar to filter or expand your search
  2. Press Enter

If it is enabled, you can also perform searches from the Mimecast search bar that appears below the regular Outlook Search bar.

Emails are only kept by Mimecast for their set retention period. If your account has a low retention period, for example S1 only provides 30 days, you may not see older emails in this search.

On-Hold Queue

If Mimecast is acting as your email gateway, you will often have messages held by the Email Security service for potential spam or phishing. From within the Mimecast for Outlook plugin, you can review your hold queue with the ability to preview messages before releasing.

  1. Select the Mimecast ribbon
  2. Select On Hold Messages

  1. If you are reviewing queue that you are a Moderator for, select Moderated On Hold from the left-hand menu

  1. Select an Email to review
  2. Select one of the following options:
    1. Reject: Deletes the message
    2. Release: Delivers the message to your Inbox
    3. Spam: Allows you to report the email as spam or phishing

Note: From the Release and Reject menus, you can also choose to block or permit emails from that sender or domain going forward. This will add an entry for this address to your Managed Senders list.

Managed Senders

The Managed Senders list is a list of email addresses and domains that either been permitted or blocked for your account. This list will only apply to your own email account, with each user maintaining their own list.

The Managed Senders list can be overridden by the Global Blocked Sender or Permitted Sender policies set by your admin. Some other policies set by your admin can also result in your list being ignored.

  1. Select the Mimecast ribbon
  2. Select Managed Senders

  1. Select the list you want to manage from the left-hand menu:
    1. Blocked: All emails from these email addresses and domains are rejected by Mimecast
    2. Permitted: Emails from these email addresses and domains are allowed through spam scanning policies automatically
    3. Auto Permitted: This list is automatically populated by Mimecast. Emails from these email addresses and domains are allowed through spam scanning policies automatically

You can add an entry by selecting the Add Blocked/Permitted button in the upper right.

You can remove an entry by selecting the entry and selecting the Remove button in the upper right.

Secure Messaging

If your account is enabled for the Mimecast Secure Messaging service, you will also have an option under the Mimecast ribbon to Send Securely. This will show when you are writing a new email.

From this menu, you can select the Secure Messaging policy to apply to that specific email.


If your Mimecast Admin has set this service up for you, Mimecast for Outlook will automatically connect you to Mimecast servers when an issue is detected with your normal mail server. During this time, you will generally be able to use your mailbox as normal.

If this is not automatically trigger and your admin has enabled this, you can manually switch Outlook to Continuity Mode by selecting Activate Continuity in the Mimecast ribbon.