Requirements and supported environments

MailTail is an Outlook add-in for Microsoft 365 organisations. You add it once from a single web address, so there's nothing to install on each device, and it runs in Outlook on Windows, Outlook on Mac, and Outlook on the web.

What you need

• A Microsoft 365 (Exchange Online) mailbox. MailTail applies signatures for accounts hosted in Microsoft 365. Personal Outlook.com accounts and on-premises-only Exchange mailboxes aren't supported.
• A supported version of Outlook (see below).
• The add-in installed, either rolled out by an administrator for the organisation or added by an individual user. See Installing the Outlook add-in.

Supported Outlook clients

MailTail runs in all of these:

• Outlook on the web (outlook.office.com)
• New Outlook on Windows
• Classic Outlook on Windows (keep Outlook updated)
• Outlook on Mac

Keeping Outlook up to date matters most on Classic Outlook for Windows. Older builds can behave inconsistently with add-ins in general.

Administrator access

To roll MailTail out for a whole organisation, you need Microsoft 365 administrator rights to deploy from the admin centre. Individual users can add it to their own mailbox without administrator access.

Connected experiences

Outlook add-ins rely on Microsoft 365's "connected experiences" setting being enabled. Most organisations have this on by default. If your administrator has turned it off, add-ins won't load, so it's worth checking when the add-in doesn't appear at all.