Microsoft Shares Workarounds for Classic Outlook Bug That Doesn't Allow Sending Emails

For some time now, Classic Outlook users have reported receiving a non-delivery report (NDR) error message when sending or replying to emails. Users affected by this Classic Outlook bug usually come across an error message that reads:

This message could not be sent. Try sending the message again later or contact your network administrator. You do not have the permission to send the message on behalf of the specified user. Error is [0x80070005-0x0004dc-0x000524].

Microsoft has now acknowledged the issue and noted that “the issue may happen more consistently if the Outlook.com account is in an Outlook Profile with another Exchange account.” While the company is investigating the issue and working on a permanent fix, it recommends a few workarounds for affected users (via Neowin).

Workaround 1:

1. Compose a new email.
2. Click the From dropdown, choose Other Email Address…, then select From….
3. In the Address Book: field, pick the Global Address List for the other Microsoft 365 account in your profile. Select the email address that triggers the NDR, then click OK twice.
4. Send the email.

Workaround 2:

1. Remove the Microsoft 365 account Address Book so Outlook won’t check it when sending.
2. Go to the Inbox of your Outlook.com account.
3. On the Outlook ribbon, click Address Book under the Find column.
4. Select Tools > Options > Custom.
5. Remove all items linked to the Global Address List and click OK to save.
6. For more details, see the forum thread: Error is [0x80070005-0x000004dc-0x00000524].

Workaround 3:

• Verify the change by opening Address Book > Offline Address Book; once the Outlook.com account no longer appears, the NDR should stop..
• Hide the Outlook.com contact from the Microsoft 365 Global Address List (GAL).
• Sign in to the Microsoft 365 Admin Center with your admin account.
• Navigate to Admin Centers > Show All > Exchange.
• In the Exchange Admin Portal, select Contacts.
• Find the contact linked to the NDR email address and open it.
• Click Manage hide from GAL, toggle Hide from Global Address List to On, and save.
• To update Outlook, go back to your profile, select the Microsoft 365 Inbox, then click Send/Receive > Send/Receive Groups > Download Address Book and confirm.

Besides these workarounds, Microsoft also recommends that affected users switch to Outlook on the web, create a fresh Outlook profile, or move to the new Outlook app for Windows to bypass the issue entirely. Speaking of issues, let’s not forget that Microsoft has finally fixed the Teams Meeting Add-in problem affecting Classic Outlook users.