Outlook Tenant Error (550 5.7.708 Access Denied)

title: "Outlook Tenant Error (550 5.7.708 Access Denied)"
description: Resolve the Microsoft 365 Outlook tenant error 550 5.7.708 Access Denied and reconnect the mailbox in SalesBlink.

Overview

This error means Microsoft has blocked outgoing email traffic from your account because the IP address it is sending from has a low reputation. According to Microsoft, this most commonly affects new customers and trial subscriptions on Microsoft 365. Learn more from Microsoft.

Important: This error cannot be resolved by a regular user. Only an email admin in your organisation can fix it. If you are not the admin, forward this article to whoever manages your Microsoft 365 account.

If you are on a Microsoft 365 trial subscription

Contact Microsoft Support and request an IP address exception. Microsoft will grant temporary access until you assign proper Exchange Online licenses to the account.

To contact Microsoft Support as an admin:

1. Log in to the Microsoft 365 Admin Center at admin.microsoft.com.
2. Go to Support → New service request.
3. Explain that you are receiving error 550 5.7.708 on a trial subscription and request an IP exception.

If you are on a paid Microsoft 365 subscription

A paid subscription receiving this error may indicate a reputation issue with your sending IP. Contact Microsoft Support via the Admin Center using the same steps above and reference error code 550 5.7.708.

After the error is resolved

Once Microsoft has lifted the block, reconnect the affected mailbox in SalesBlink:

1. Go to Outreach → Email Senders.
2. Find the affected Outlook or Microsoft 365 sender.
3. Edit the sender and click Save to reconnect (or re-authorize for OAuth).

See also Understanding Email Account Disconnection Reasons in SalesBlink.

Updated on: 18/08/2026