无人值守升级发送邮件失败，mailx可正常发送求助

Hey there, I’ve dealt with this exact frustration before—when mailx sends emails fine via your .mailrc, but unattended-upgrades just won’t cooperate. Let’s break down the fixes step by step:

1. Check Unattended-Upgrades Core Configuration #

First, make sure unattended-upgrades is even set up to send emails correctly. Open its main config file:

sudo nano /etc/apt/apt.conf.d/50unattended-upgrades

Look for these lines and verify they’re set properly:

Unattended-Upgrade::Mail "your-email@example.com";  # Double-check this address!
Unattended-Upgrade::MailReport "on-change";  # Or "always" if you want regular updates

Save and exit if you made changes.

2. Unattended-Upgrades Doesn’t Read Your User’s .mailrc #

Here’s the key: unattended-upgrades runs as root, so it doesn’t pick up the .mailrc in your regular user directory. You have two options here:

• Copy your .mailrc to root’s home:

  cp ~/.mailrc /root/.mailrc
  chmod 600 /root/.mailrc  # Critical for security—only root can read it
  

  Then test if root can send emails with mailx:

  sudo mailx -s "Root Mail Test" your-email@example.com <<< "This is a test from root"
  

  If this works, unattended-upgrades might just need a nudge to use mailx.

3. Force Unattended-Upgrades to Use mailx #

By default, unattended-upgrades might use sendmail or another mail agent instead of mailx. Tell it to use mailx explicitly by adding this line to /etc/apt/apt.conf.d/50unattended-upgrades:

Unattended-Upgrade::MailCommand "/usr/bin/mailx -s 'Unattended Upgrade Report' %s";

The %s is a placeholder that gets replaced with your email address from the Unattended-Upgrade::Mail line.

4. Debug with a Dry Run #

Trigger a test run to see exactly what’s going wrong:

sudo unattended-upgrade --dry-run --debug

Check the logs for email errors afterward:

cat /var/log/unattended-upgrades/unattended-upgrades.log

Look for lines like "Failed to send email" or SMTP connection issues—this will point you to whether it’s an auth problem, server connectivity, or something else.

5. Verify SMTP Server Access #

Sometimes the issue is that your server’s IP is blocked by your email provider (e.g., Gmail, Outlook). Check your email provider’s spam folder first, then:

• Ensure your .mailrc (root’s version) has correct SMTP auth details:

  set smtp=smtp://smtp.example.com:587
  set smtp-auth=login
  set smtp-auth-user=your-smtp-username@example.com
  set smtp-auth-password=your-smtp-password
  set ssl-verify=ignore  # Or "strict" if your provider supports it
  

• If you’re using Gmail, you might need to enable app-specific passwords (if 2FA is on) or adjust account security settings to allow server-based sends.

内容的提问来源于stack exchange，提问作者user3371854