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Microsoft 365: enable SMTP AUTH and IMAP for a user

OutreachFox sends and reads mail from a Microsoft 365 (Outlook) mailbox over SMTP and IMAP. Both protocols are disabled by default on many tenants, so a Microsoft 365 administrator must enable them…

OutreachFox sends and reads mail from a Microsoft 365 (Outlook) mailbox over SMTP and IMAP. Both protocols are disabled by default on many tenants, so a Microsoft 365 administrator must enable them for each user whose mailbox you want to connect. This article covers that admin-center step.

Prerequisites

  • Global admin or Exchange admin access to the Microsoft 365 admin center (admin.microsoft.com).
  • The list of users whose mailboxes will be connected.

Steps

  1. In OutreachFox, go to Mailbox → Connect Mailbox → Office365 Outlook. Read the on-screen instructions; they tell you which settings to enable.

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  1. In a new tab, log in to the Microsoft 365 admin center.

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  1. Go to Users → Active Users.

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  1. Select the user whose mailbox you want to connect.

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  1. In the user's details panel, click the Mail tab.

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  1. Click Manage Email Apps.

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  1. Make sure Authenticated SMTP (SMTP AUTH) and IMAP are both ticked. They may already be enabled; if not, tick them.

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  1. Click Save changes and wait for the confirmation.
  2. Close the admin panel. Repeat steps 4–8 for each additional user.

Now return to OutreachFox and connect the mailbox. See Connect a Microsoft 365 / Outlook mailbox to OutreachFox.

Why this matters

  • SMTP AUTH lets OutreachFox send mail through smtp.office365.com as the user.
  • IMAP lets OutreachFox read the inbox to detect replies and bounces and to run warmup.

If either is off, the connection either fails outright or connects but never sees replies.

Tips

  • Changes can take up to 30–60 minutes to propagate across Microsoft's servers; if the connection fails immediately after saving, wait and retry.
  • Some tenants also block SMTP AUTH at the organisation level (Exchange admin center → Settings → Mail flow → "Turn off SMTP AUTH protocol for your organization"). The per-user setting overrides it, but check this if connections keep failing.
  • Security Defaults or Conditional Access policies that block "legacy authentication" can also block SMTP AUTH; exclude the sending users from those policies or use modern-auth-compatible settings.

Troubleshooting

  • Manage Email Apps is greyed out — the user has no Exchange license; assign one first.
  • Settings revert after saving — an organisation-wide policy is overriding them; see the tips above.
  • Connection still fails after enabling — see Fix mailbox disconnection errors (Google, Microsoft, SMTP).

Related articles

  • Connect a Microsoft 365 / Outlook mailbox to OutreachFox
  • Fix mailbox disconnection errors (Google, Microsoft, SMTP)
  • Common IMAP/SMTP hostnames

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