Troubleshooting SMTP setup issues

This article covers the most common errors that may occur in SMTP setup and how to resolve them.

1. General troubleshooting steps

If you are experiencing general delivery issues where emails fail to send but you don't see a specific error, try these initial troubleshooting steps:

• Double-check your SMTP settings: Ensure that your port, host, and encryption type (SSL/TLS) comply with your provider's recommended guidelines.
• Disconnect and reconnect: Many connection handshake anomalies can be resolved by resetting the sync. Navigate to Settings > My Settings > Email, select Disconnect, and then reconnect your SMTP.

2. MS Exchange SMTP issues

2.1. Authentication unsuccessful / SMTP Client Authentication disabled (error 535 5.7.139)

How to solve it: 

1. Enable Authenticated SMTP for the user:
   1. Your Microsoft 365 IT Administrator must log in to the Microsoft 365 Admin Center.
   2. Go to Users > Active Users and select your specific user profile.
   3. Open the Mail tab, and under Email apps, click Manage email apps.
   4. Check the box for Authenticated SMTP and click Save changes.
2. Verify tenant-level settings: Your IT Administrator should ensure that SMTP AUTH is not disabled globally at the organization level or blocked by Microsoft Security Defaults / Conditional Access policies.
3. Allow propagation and test:
   1. Wait 15 to 30 minutes for Microsoft's server changes to propagate.
   2. Try sending an email again from Scoro.
4. If you've completed the above steps and email sending still fails after the full propagation period has elapsed, disconnect and reconnect your SMTP setup, then try sending an email again.

2.2. Client not authenticated to send mail (Error 530 5.7.57)

How to solve it:

1. Confirm active Exchange Online mailbox & SMTP AUTH:
   1. Ensure your Microsoft account has an active Exchange Online license assigned.
   2. Verify that Authenticated SMTP (SMTP AUTH) is enabled for the mailbox and tenant in your M365 Admin Center. For more guidance, see the Authentication unsuccessful error section.
2. Match sender address or grant "Send As" permissions:
   1. Confirm that the sender email address in your Scoro profile matches the primary email of the connected Microsoft 365 mailbox.
   2. If you are attempting to send from an alias or secondary email address, your IT Admin must grant Send As delegation permissions for that address. For more guidance, see the Send As Denied error section.
3. Disconnect and reconnect using Incognito mode:
   Browser session caching can accidentally log you into the wrong Microsoft account during the OAuth flow. To resolve it:
   1. Go to Settings > My Settings > Email and click Disconnect.
   2. Open an Incognito or Private browsing window, log back into Scoro, navigate to Settings > My Settings > Email, and reconnect your Microsoft Exchange integration using the correct credentials.
4. Verify settings for manual SMTP connections:
   1. If you are configuring a custom/manual SMTP connection rather than using the standard Microsoft Exchange OAuth integration, verify that your server settings match Microsoft's required parameters:
      • Server / Host: smtp.office365.com
      • Port: 587
      • Encryption / Security: TLS (or STARTTLS)

2.3. Invalid_grant (error AADSTS65001)

If you use MS Exchange through Entra Enterprise and receive an invalid_grant error (error code AADSTS65001) while setting up your Microsoft Exchange SMTP server, it means that the Scoro application doesn't have the necessary administrator consent in your Entra Admin Center settings.

How to solve it:

1. Grant the permission:
   1. In the Entra Admin Center, select Show all to display all Admin Centers.
   2. In the side menu, navigate to Entra ID > Enterprise apps.
   3. Click on the Scoro app, then open the Permissions section in the side menu.
   4. Click the blue Grant admin consent button. The permissions request screen will appear – click the Accept button.
2. Retry the setup: Try setting up your MS Exchange SMTP in Scoro again. Since the Scoro app now has admin permissions, the SMTP setup should work successfully.

For more detailed guidance, see the Grant tenant-wide admin consent to an application article on Microsoft Learn.

2.4. Send as Denied (error 5.2.252)

There are two ways to solve this issue:

• Match your "From" address:
  • The simplest fix is to ensure the "From" address in your Scoro settings matches the primary email address of your authenticated Microsoft mailbox.
• Grant Send As delegation:
  • If you need to send emails using an alias or another address, your IT Administrator must log into the Exchange Admin Center or M365 Admin Center and grant Send As permissions to your authenticated mailbox for the target alias/address.
  • It can take up to 60 minutes for permission updates to propagate across Microsoft's systems. You do not need to disconnect or reconnect your SMTP connection in Scoro for this change to take effect.

2.5. Application client secret expired (Error AADSTS7000222)

To resolve this issue, please contact our Support team via this contact form.