How to Enable Port 587

1. Email Servers

Postfix (Linux):

  • Edit /etc/postfix/
  • Add or uncomment the line: submission inet n - y - - smtpd
  • In /etc/postfix/ add:
    smtpd_tls_security_level = may
    smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
    smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
  • Restart Postfix: sudo systemctl restart postfix

Microsoft Exchange:

  • Open Exchange Management Shell
  • Run: Set-ReceiveConnector "Client Frontend <ServerName>" -ProtocolLoggingLevel Verbose
  • Then: Set-TransportService <ServerName> -ReceiveProtocolLogPath "C:\Program Files\Microsoft\Exchange Server\V15\TransportRoles\Logs\ProtocolLog\SmtpReceive"

2. Firewalls


  • Open Windows Firewall with Advanced Security
  • Click *Inbound Rules* –> *New Rule*
  • Choose *Port* –> *TCP* –> Enter *587*
  • Allow the connection
  • Apply to all profiles
  • Name the rule *SMTP Port 587*

Linux (iptables):

  • Run: sudo iptables -A INPUT -p tcp --dport 587 -j ACCEPT
  • Save rules: sudo service iptables save

3. Email Clients


  • Go to File –> Account Settings –> Account Settings
  • Select your email account –> Change
  • Click *More Settings* –> *Advanced* tab
  • Change *Outgoing server (SMTP)* to 587
  • Under *Use the following type of encrypted connection* select *TLS*

Gmail (Web):

No client side configuration needed but make sure your domain’s SPF record includes the IP of your SMTP server.


  • Go to Tools –> Account Settings
  • Under *Server Settings* change *Port* to 587
  • Select *StartTLS* for *Connection security*

Leave a Reply

Your email address will not be published. Required fields are marked *