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Troubleshooting "No reply address provided" error when connecting Outlook Calendar

Overview

If you're seeing a Microsoft sign-in error when trying to connect your Outlook calendar to Brevity, this article explains how to resolve it. This issue affects users whose organization manages Microsoft accounts through Azure Active Directory (also called Microsoft Entra ID) and has policies that restrict third-party app access.

Symptoms

You may be experiencing this issue if:

  • You click Set up next to Microsoft Outlook on Brevity's Connections page
  • You're redirected to Microsoft sign-in and select your work account
  • You see the following error before the connection completes:
 
 
AADSTS900971: No reply address provided.
  • No approval prompt or consent screen appears — the error shows immediately

Note: This issue only affects users with work or school Microsoft accounts managed by an organization. Personal Outlook.com accounts follow a different flow.

Cause

Brevity connects to Outlook Calendar through a calendar provider called Nylas. When you authenticate, Microsoft needs to approve Nylas's application before granting access to your calendar.

Some organizations configure their Microsoft tenant to block third-party apps by default — either preventing users from approving apps on their own, or blocking the consent prompt from appearing entirely. When this policy is active, Microsoft rejects the request before the connection can complete.

This is a tenant-level security policy set by your IT team, not an issue with Brevity or your account.

Solution

There are three paths to resolution depending on your organization's preferences. Start with Option 1, which is the most common fix.

Option 1: Enable admin approval requests, then request access (Recommended)

This two-step process allows you to submit an approval request that your IT admin can grant from the Azure portal.

Your IT admin does this first (one-time setup):

  1. Log in to https://portal.azure.com
  2. Navigate to Azure Active Directory > Enterprise Applications > User Settings
  3. Set "Users can request admin consent to apps they are unable to consent to" to Yes
  4. Save the changes

Then you (the end user) do this:

  1. Go back to Brevity's Connections page and click Set up next to Microsoft Outlook
  2. Sign in with your Microsoft work account as usual
  3. This time, you should see a "Request approval" screen — click Request approval
  4. Your IT admin will receive an email notification with a link to review the request

Your IT admin approves the request:

  1. Log in to https://portal.azure.com
  2. Navigate to Azure Active Directory > Enterprise Applications > Admin consent requests > All (preview)
  3. Find the pending request for the Nylas application and approve it
  4. Once approved, you'll be notified and can complete the Outlook connection in Brevity

Tip for IT admins: After approving, you can use Assign Users and Groups on the application to pre-approve it for your entire organization, so other users won't need to go through this process.

Option 2: Allow users to self-approve apps (bypasses the request flow)

If your IT admin prefers to allow users to approve third-party apps without going through the request process:

  1. Log in to https://portal.azure.com
  2. Navigate to Azure Active Directory > Enterprise Applications > Consent and Permissions > User consent settings
  3. Set "Allow user consent for apps" to allow consent for verified apps (or all apps)
  4. Once configured, users can connect Outlook to Brevity without admin involvement

Note: Choosing "Allow user consent for verified apps only" (the default option) will work for Nylas, as Nylas is a Publisher Verified Azure application. The most permissive option allows consent for all apps regardless of verification status.

Option 3: Contact your IT team directly

If you're not able to complete either option above, send your IT administrator the following information so they can locate the blocked sign-in attempt and take action:

  • Error code: AADSTS900971
  • What to look up: Azure Active Directory > Monitor > Sign-in logs, filtered by your email address and the date/time of the failed attempt
  • What they're looking for: The sign-in failure log entry, and any Conditional Access policy applied at the time
  • What they need to do: Approve the Nylas application for your tenant using one of the options above

Verify It Worked

After completing the steps above:

  1. Go to Brevity's Connections page
  2. Click Set up next to Microsoft Outlook
  3. Sign in with your Microsoft work account
  4. You should be prompted to grant calendar permissions — click Accept
  5. You'll be redirected back to Brevity and your Outlook calendar will appear as connected

Still having trouble?

If you've completed the steps above and the error persists, contact Brevity support and include:

  • Your email address
  • The date and time of the failed attempt
  • A screenshot of any error message you see
  • Confirmation of which option your IT admin completed

Help us improve this article: This guide was written based on the first reported case of this issue. If you followed these steps, please let your Brevity contact know whether they resolved the problem — your feedback helps us keep this documentation accurate.

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