Apple Mail usually works well, but when it stops sending emails the cause is almost always SMTP settings, a temporary server issue, an authentication problem, or a network/security conflict. The most common symptom is a message stuck in Outbox or repeated “Cannot Send Mail” errors.
This guide walks through the fastest fixes first, then deeper checks if the issue keeps returning. If you manage multiple email accounts and sending failures keep disrupting your workflow, it may be worth switching to a more reliable multi-account email client with a unified inbox and privacy-first defaults.
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Why My Mac Mail Won’t Send Email?
Are you wondering why the email you’re trying to send just won’t budge from your outbox? Or maybe you’ve managed to send it, but the recipient claims they never received it. If so, you may be experiencing an issue with Apple Mail not sending emails—a common problem that leads many users to consider an Apple Mail vs Canary Mail comparison.
There are several common reasons why your Mail app might stop delivering messages:
Incorrect SMTP Settings
Mac Mail handles outgoing emails using the Simple Mail Transfer Protocol (SMTP). Incorrect SMTP settings are among the most frequent reasons why Apple Mail isn’t sending emails. Incorrect server addresses, port numbers, or security protocols can prevent emails from being sent entirely.
Software Conflicts
Conflicts between the Mail app and other software installed on your Mac, such as third-party security software or system utilities, can lead to syncing problems. These conflicts may interfere with the proper functioning of the Mail app and prevent it from connecting to the SMTP server.
Firewall Block
Firewalls and security software can sometimes block certain network ports (like 25, 465, or 587) used for sending emails. If they're configured too strictly, they can block legitimate connections required for your outgoing mail server to function.
Internet Connectivity Issues
A stable internet connection is essential for your Mail app to work properly. If your device has internet connectivity issues, such as a weak Wi-Fi signal or network congestion, it can disrupt the communication between your device and the email server.
How to Fix Apple Mail Not Sending Emails
If you’re experiencing issues, there are several troubleshooting solutions you can implement to solve this frustrating problem.
Check for Status Messages
Check the status icon next to your account’s inbox in the Mail sidebar. The status will often provide a specific error message that pinpoints whether the issue is related to your password, the server, or your network.
Restart the Mail App
This prompts Mail to refresh. You can also quit the app completely and open it again.
Test Server Connection With Connection Doctor
Apple Mail comes with a built-in diagnostic tool called Connection Doctor. Use this to check the status of your email server connections in real-time. It helps you pinpoint if the problem lies with the incoming or outgoing servers.
Reset Firewall and Security Settings
Ensure that your firewall is not blocking Mail. Confirm that the necessary ports for your email provider are open and that the Mail app has the proper permissions to communicate with the email server.
Remove and Reconnect Your Email Account
If other solutions fail, removing and reconnecting your email account can refresh your settings and clear corrupted account data. This is often the "reset" needed to fix persistent sending failures.
Consider An Alternative If Sending Failures Keep Returning
If Apple Mail keeps failing to send, especially across multiple inboxes, the issue is often not just one setting. It is the overall reliability of the workflow: account auth refreshes, SMTP handshakes, network conflicts, and edge cases that keep repeating.
If you want a calmer daily experience, consider an email client built for multi-account reliability:
- Unified inbox for multiple providers (Gmail, iCloud, Outlook, Yahoo) in one place.
- Privacy-first protections by default, ensuring a strict "No data harvesting" stance.
- Optional AI help for drafting and summaries (use it only if you want).
Canary Mail is a modern multi-account email client designed to reduce inbox friction and help you stay consistent across your daily workflow.
If you are looking for a more dependable way to handle your communication, watch this overview of how Canary Mail uses AI-powered features to simplify email management. This tutorial explores how you can use the Co-pilot to write formal emails in seconds, summarize long threads, and automatically prioritize your most important replies to eliminate busywork.
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Mail App Not Sending Emails, the Bottom Line
Apple Mail sending issues are usually fixable, but they are still disruptive when they repeat. Start with the quick checks in this guide, then verify SMTP, authentication, and network conflicts if your Outbox keeps getting stuck.
If sending failures keep coming back and you rely on email for work, it may be time to switch to a calmer, more reliable multi-account workflow with privacy-first defaults. Canary Mail is a strong option to test, and AI features are optional.
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Apple Mail Not Sending Emails, the FAQs
Why are my outgoing emails not being sent on Apple Mail?
Outgoing email issues can stem from incorrect SMTP settings, network issues, or server problems. Ensure your SMTP settings are accurate and check your internet connection status.
How do I fix the outgoing mail server on Mac?
Go to Settings > Accounts, select the account, and verify the SMTP settings. Ensure the server address, username, password, and port are correct according to your provider’s requirements.
Why is my mail stuck in the outbox on my Mac?
This is typically due to SMTP server issues, poor connectivity, or large attachments. Verify your settings or try removing and reconnecting the account to refresh the connection.
How do I enable SMTP on my Mac?
SMTP is enabled by default. You can manage or update these settings by navigating to Mail > Settings > Accounts and selecting the Server Settings tab for your specific account.