Mimecast for Outlook - Continuity Overview

This article contains information on Continuity Mode in Mimecast for Outlook, including how it works, considerations, phases of continuity mode, managing distribution lists, and emailing during continuity events to ensure uninterrupted email access during outages.

Also see Continuity - Overview.

How Continuity Works

Mimecast for Outlook checks for continuity events every three minutes. Once Continuity Mode is disabled, you'll automatically be switched into normal operating mode, and messages will travel through your organization's email server again.

When Continuity Mode is triggered, the following behavior is experienced:

• Microsoft Outlook is switched to offline mode.
• While Exchange is offline, Mimecast for Outlook mailbox monitoring functionality continues to check for new messages.
• New messages received via Mimecast populate the Microsoft Outlook Inbox.
• Mimecast for Outlook monitors for and resolves duplicate messages, from five minutes before the start of the Continuity Event, until ten minutes after the Continuity Event ends.
• If stubbing is in use, stubbed messages are not monitored for duplicates.
• Delegate mailbox functionality operates the same as if continuity mode is inactive.
• Messages composed are transmitted directly via Mimecast. A copy of the message is populated into the Sent Items folder in Microsoft Outlook.
• Exchange rules are not applied whilst Mimecast for Outlook is in continuity mode.

Considerations

• Mimecast for Outlook can only enter continuity mode if Microsoft Outlook has the Use Cached Exchange Mode option enabled in your Account Settings. If Microsoft Outlook is in non-cached mode, continuity functionality is not available.
• Should a mailbox be required to be rebuilt at any point, mailbox monitoring and duplicate message resolution will not run in this scenario.
• If the BCC to mail server setting is enabled in the Mimecast Administration Console, the user will receive a copy of the message in their Inbox. This may be disabled as required.

Phases of Continuity Mode

Using a Continuity Event, Mimecast for Outlook can be forced into continuity mode, which is helpful if there is a server outage or planned maintenance to the Exchange server. There are three main phases for the Mimecast for Outlook continuity service:

Before the Continuity Event

Mimecast checks message folders for messages delivered before the Continuity event, reconciling duplicates and resulting in a list of undelivered emails for Outlook that are then sent to the user's inbox. Due to mailbox rules and bulk email insertion, some duplicate messages are delivered. Mimecast for Outlook errs on the side of caution, delivering messages as duplicates rather than not delivering them. However, the occurrence of this should be minimal.

During a Continuity Event

Mimecast for Outlook monitors Mimecast for new messages and delivers them to the user's Inbox during a Continuity event. It checks with the Mimecast Service every minute to see if new messages have arrived and are placed in the Inbox. Mailbox rules that move items out of the Inbox may not work during a Continuity event, so users must manually move messages to display in the appropriate folders. Continuity mode only sends emails (IPM.Note) and Calendar items (Outlook 2013 onwards), and any other file types will not be delivered until after the event. After the message detail collection process, Mimecast for Outlook starts monitoring the user's Inbox, adding any messages found in Mimecast to the user's primary Inbox (OST file). Outbound messages will continue to be sent via Mimecast.

Ending a Continuity Event

Once the Continuity event ends, Outlook will again deliver messages to end users via Exchange. For 10 minutes after the Continuity event has ended, Mimecast for Outlook monitors the incoming messages to ensure that messages that have already been delivered via Mimecast for Outlook during the outage are not re-delivered.

As with the first phase, messages may arrive in non-Inbox folders. While this isn't common, duplicate messages may appear in folders outside the Inbox during this phase.

Distribution Lists

Mimecast allows users to expand distribution lists during continuity events by selecting the Expand Distribution Lists during Continuity Event option. Users can access all emails sent to their mail-enabled group or distribution list during an active Continuity event. These emails are available via all Mimecast applications, including the local inbox when Mimecast for Outlook is in Continuity mode. This also applies to delegate mailboxes. Active Directory synchronization is required for group membership based on the last successful sync.

Emailing during a Continuity Event

You can use Online Inbox and Online Sent Items during a Continuity event, including delegate mailbox access that an administrator has assigned you.

You can access your Online Inbox or Online Sent Items folder, by using the following steps:

1. Open the Mimecast tab in Microsoft Outlook.
2. Select the relevant menu item:

• • Online Inbox
  • Online Sent Items

Each view displays:

• Items sent or received over the last 30 days. Items older than this may be found using an archive search.
• The last 100 messages (by default) are displayed in reverse date order.
• The most recently received email is displayed first. To access more messages, scroll to the bottom of the list, and more items will be retrieved.

With the messages displayed, you can:

• Compose a new message.
• Block a sender or domain. See Blocking Senders.
• Mark a sender or domain as spam. See Blocking Senders.
• Reply, Reply All, or Forward a message.
• Print or Save a message.
• Preview a message by clicking on it.
• Open a message by double-clicking on it.