Power Automate integrates with Outlook to automate email-related tasks like sending emails, reading inbox messages, moving emails, and triggering flows based on emails. However, sometimes the Outlook email action fails, leading to flow execution errors.
This guide will cover:
Common causes of Outlook email action failures
Step-by-step troubleshooting and solutions
Best practices to prevent future email issues
Step 1: Identifying the Outlook Email Failure
1.1. Check the Flow Run History
- Open Power Automate → Go to My Flows.
- Select the failing flow → Open Run History.
- Find the Outlook email action and check the error message.
Step 2: Fixing Common Outlook Email Action Failures
2.1. Authentication or Permission Issues
Problem: Power Automate cannot authenticate with Outlook due to expired credentials or missing permissions.
Solution:
- Reconnect the Outlook connector:
- Go to Data → Connections.
- Find Office 365 Outlook → Click Reconnect.
- Ensure the user has email sending permissions in Exchange Admin Center.
- If using a shared mailbox, ensure the account has Send As or Send on Behalf permissions.
Tip: Use a service account to prevent authentication disruptions due to password changes.
2.2. Incorrect Email Address Format
Problem: The email recipient’s address is invalid or incorrectly formatted.
Solution:
- Ensure email addresses are correct and formatted properly (e.g.,
user@example.com). - If pulling email addresses dynamically from SharePoint or Excel, ensure values do not contain spaces or special characters.
- Use a “Condition” action to validate email addresses before sending.
Example Fix:
Before sending, check if the email address is blank or contains invalid characters.
2.3. Email Sending Limits Exceeded
Problem: The flow is trying to send too many emails in a short time, exceeding Outlook’s sending limits.
Solution:
- Limit the number of emails sent per minute to avoid throttling.
- Add a “Delay” action between email sends to slow down execution.
- If sending bulk emails, consider using distribution lists instead of individual emails.
Tip: Microsoft Outlook typically limits sending to 10,000 emails per day or 30 messages per minute.
2.4. Shared Mailbox or Delegation Issues
Problem: The flow is trying to send an email from a shared mailbox, but the user lacks permissions.
Solution:
- In Exchange Admin Center, assign the user:
- Send As permission → Allows sending emails as the shared mailbox.
- Send on Behalf permission → Sends emails showing “on behalf of” the shared mailbox.
- Use the “Send an email from a shared mailbox” action in Power Automate instead of the regular “Send an email” action.
Example Fix:
Use “Send an email from a shared mailbox” → Enter the mailbox name in the “From” field instead of the default user account.
2.5. Attachments Too Large
Problem: The email contains attachments exceeding Outlook’s file size limits.
Solution:
- Ensure total email size does not exceed 25 MB (Outlook limit).
- Compress large files before attaching.
- If files are too large, store them in OneDrive or SharePoint and send a download link instead.
Example Fix:
Replace direct attachment with a OneDrive link using the “Create share link” action in Power Automate.
2.6. Spam Filtering or Blocked Domains
Problem: The email is blocked due to spam filtering, blacklisted domains, or restricted content.
Solution:
- Avoid using spam trigger words like “Free,” “Limited Offer,” or excessive capital letters.
- If emails are flagged as spam, request whitelisting from IT or configure Exchange Online Protection (EOP) settings.
- If sending to external recipients, ensure their email provider is not blocking messages from your domain.
Tip: Test email delivery using an alternative email address before automating large-scale email sends.
2.7. Flow Execution Delays or Timeouts
Problem: The email action takes too long, causing the flow to timeout.
Solution:
- Use asynchronous actions (e.g., sending emails in a parallel branch) to avoid long execution times.
- If fetching email content dynamically, reduce the amount of processed data to speed up execution.
- Check for loops processing too many emails and optimize filtering conditions.
Step 3: Preventing Future Outlook Email Failures
✅ 3.1. Use a Dedicated Service Account
- Avoid using personal accounts for authentication.
- Use a service account with minimum required permissions.
✅ 3.2. Monitor Email Sending Limits
- Set alerts for high email traffic to avoid throttling.
- Distribute email sends over a longer period instead of bulk sending.
✅ 3.3. Validate Email Addresses Before Sending
- Use a “Condition” action to check if recipient emails exist.
- Ensure emails do not contain spaces, invalid characters, or typos.
✅ 3.4. Enable Power Automate Logs and Alerts
- Set up alerts for failed email actions.
- Regularly review Power Automate run history for recurring failures.
✅ 3.5. Use Alternative Notification Methods
- If email fails, consider sending Teams notifications or logging the issue in a SharePoint list for tracking.