Mail Problems in Catalina & Fixes

Mail problems in Catalina (macOS 10.15) are common, but most are fixable. This article explains the typical issues—crashes, slow performance, missing messages, and connection errors—and gives you the exact steps to resolve them.

Background: Why Catalina Mail Is Different

macOS Catalina (10.15) replaced iTunes and introduced a new system volume structure. For Mail, this meant a switch to 64-bit only, which broke many older plugins and added stricter security checks. The Mail app itself also moved to a new storage format (Mail Data V2) that can become corrupted after a failed upgrade. Understanding this helps explain why some fixes work and others don’t.

Common Mail Problems in Catalina

Mail crashes on launch – often due to a corrupted envelope index or a problematic plugin.
Mail is slow or unresponsive – usually caused by a large mailbox or a stuck server connection.
Messages missing or not syncing – typically a sync conflict or account settings issue.
Connection errors (e.g., “Cannot connect to server”) – often a password or security certificate problem.
Search not working – the Spotlight index for Mail may be broken.
Attachments won’t download – often a temporary server issue or a full disk.

How to Fix Mail Crashes on Launch

Restart Mail in Safe Mode – Hold Shift while opening Mail to temporarily disable plugins. If it works, remove or update your plugins.
Repair the Mail database – In Mail, go to Window > Connection Doctor and check for errors. Then quit Mail and hold Option while reopening it to access the rebuild prompt.
Delete the envelope index – Quit Mail, then in Finder press Cmd+Shift+G and go to ~/Library/Mail/V10 (or V9). Move the folder named MailData to the Desktop, then reopen Mail. It will rebuild the index.

How to Fix Slow Mail Performance

Rebuild the mailbox – Select the problematic mailbox, then go to Mailbox > Rebuild. This can take time but often resolves lag.
Remove old attachments – Use Mailbox > Remove Attachments to free up space.
Check for large mailboxes – Mail > Preferences > Accounts > Mailbox Behaviors shows local storage. If a mailbox is huge, consider archiving old messages.
Disable unnecessary plugins – Go to Mail > Preferences > General and uncheck “Load remote content” if you don’t need it.

How to Fix Missing or Unsynced Messages

Check Connection Doctor – Open Window > Connection Doctor and look for red dots next to your accounts.
Toggle the account off/on – In Mail > Preferences > Accounts, uncheck “Enable” for the account, wait a few seconds, then re-enable it.
Verify server settings – Ensure your incoming/outgoing server addresses and ports are correct. You can find these from your email provider’s help page.
Check if the issue is server-side – Log into your webmail. If messages are missing there too, the problem is on the server, not Mail.

How to Fix Connection Errors

Update your password – If you changed your email password recently, Mail may still be using the old one. Go to Mail > Preferences &em; Accounts and update it.
Check your keychain – Sometimes the saved password is corrupted. Open Keychain Access, search for your email account, and delete the entry. Then re-enter your password in Mail.
Disable SSL temporarily – In Mail > Preferences > Accounts > Server Settings, uncheck “Use SSL” to test if it’s a certificate issue. Re-enable after testing.
Check your firewall – Make sure your firewall isn’t blocking Mail’s connection to your email provider.

How to Fix Search Not Working

Rebuild the Spotlight index – Go to System Preferences > Spotlight > Privacy, add your Mac’s hard drive, then remove it. This forces a re-index.
Rebuild Mail’s envelope index – As described above, delete the MailData folder. This often fixes search issues.
Check if the issue is account-specific – Search works differently for Gmail and Exchange accounts. If it’s only one account, try removing and re-adding it.

Frequently Asked Questions

Why does Mail keep asking for my password?

This usually means the saved password in Keychain is outdated or incorrect. Update the password in Mail preferences, and if that fails, delete the Keychain entry for that account and re-enter it.

Can I downgrade back to macOS Mojave to fix Mail?

Yes, but it’s a drastic step. You would need to erase your Mac and reinstall Mojave. Before doing that, try the fixes above—most Mail issues can be resolved without downgrading.

Does Mail in Catalina support Microsoft 365 accounts?

Yes, Mail supports Microsoft 365 accounts, but you may need to enable “Allow less secure apps” on your Microsoft account if you’re using basic authentication. For modern accounts, OAuth is supported.

Why are my emails not sending?

Check your SMTP server settings. In Mail preferences, go to Accounts > Server Settings and verify the outgoing server address and port. Also ensure your password is correct.

How do I backup my Mail before trying fixes?

You can export mailboxes by selecting them and choosing Mailbox > Export Mailbox. Also, copy the ~/Library/Mail folder to an external drive. This preserves all your messages and settings.

Will Apple support fix Mail issues for free?

Apple Support can help with troubleshooting over the phone or chat for free, but if your Mac is out of warranty, a visit to an Apple Store may incur a fee. Many issues can be resolved with the steps above.

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