Laravel生产环境（AWS）Office365 SMTP突然连接超时求助

Hey there, sorry to hear you're stuck with this unexpected SMTP issue—let's walk through the most likely fixes based on common pitfalls for Laravel + Office 365 + AWS setups:

1. Check AWS Network Restrictions (Most Common Culprit) #

AWS has strict outbound limits on port 25 to combat spam, and even if it worked before, temporary restrictions or accidental security group changes can break it. Try these steps:

• Switch to an allowed port: Office 365 supports port 587 (TLS) and 465 (SSL) which AWS doesn't restrict. Update your .env config:

  MAIL_PORT=587
  MAIL_ENCRYPTION=tls
  

• Verify Security Group/NACL Rules: Ensure your EC2 instance's security group allows outbound traffic on port 587 (or 465) to any destination (or specifically to smtp.office365.com). Double-check your VPC's Network Access Control Lists (NACLs) for any outbound blocks.

2. Office 365 Tenant/Account Security Checks #

Office 365's security systems can lock down access without warning:

• Check for account restrictions: Log into the Office 365 Admin Center, navigate to the nao_responda@primorossi.com mailbox, and confirm it hasn't been restricted from sending emails or flagged for suspicious activity.
• Resolve security prompts: Try logging into the mailbox via Outlook Web App—if there's a pending two-factor authentication prompt or a request to approve the AWS server's location, complete those steps.
• Verify send limits: Ensure the account hasn't hit Office 365's daily email sending quota.

3. Laravel & Server-Level Debugging #

• Clear config cache: Old cached config can cause unexpected behavior. Run this on your production server:

  php artisan config:clear
  

• Test raw connection: Bypass Laravel to confirm the network issue directly. On your AWS server, run:

  telnet smtp.office365.com 587
  # Or using netcat if telnet isn't installed
  nc -zv smtp.office365.com 587
  

  If this times out, the problem is definitely network-related (not Laravel/SwiftMailer).
• Check server firewall: Ensure iptables, ufw, or any security tools like fail2ban aren't blocking outbound SMTP traffic to Office 365's IPs.

4. DNS Resolution Issues #

• Test DNS lookup: On your AWS server, run:

  nslookup smtp.office365.com
  dig smtp.office365.com
  

  Confirm the resolved IPs are reachable. If you see invalid or unreachable IPs, try flushing the server's DNS cache or switching to AWS Route 53/Google DNS (8.8.8.8) for more reliable resolution.

5. Alternative: Use AWS SES as a Relay #

If all else fails, consider using AWS SES to handle your email delivery—AWS integrates seamlessly with SES, avoiding port 25 restrictions. You can either:

• Switch Laravel's mail driver to ses (requires configuring AWS credentials)
• Set up SES as an SMTP relay to forward emails to Office 365.

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