Port587— SMTP submission / STARTTLS
Le port 587 sert à la soumission de messages, généralement d’un client de messagerie à son fournisseur. Distinguez cet usage du relais entre serveurs sur le port 25.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
Utilisez les réglages STARTTLS et d’authentification exigés par le fournisseur. STARTTLS fait passer la session SMTP au chiffrement, contrairement au TLS implicite sur 465.
Important limitations
Un numéro de port n’impose pas le chiffrement. Si la négociation TLS échoue, corrigez la configuration au lieu de transmettre les mots de passe en clair.
Read-only checks: run on the server host
Choose the commands for your OS. Check TCP and UDP separately. No result is not a lasting availability guarantee; inspect host and container separately.
Linux
sudo ss -ltnp 'sport = :587'macOS
sudo lsof -nP -iTCP:587 -sTCP:LISTENWindows PowerShell
Get-NetTCPConnection -LocalPort 587 -State ListenSources and review
Sources checked on:
This review covers the explanations and sources on this page, not your device or every community software entry below.
Logiciels utilisant ce port (3 logiciels)
Community software entries: links are references, not individual verification.
Conseils d’utilisation
- Avant d’utiliser le port 587, vérifiez qu’il n’est pas occupé par d’autres services
- En cas de conflit de ports, envisagez d’utiliser d’autres ports ou d’arrêter le service qui occupe le port
Questions fréquentes
What is port 587 used for?
Port 587 sits in the Email & Messaging category. This page lists the registered purpose and the software commonly associated with it; to see what is actually listening on a specific machine, check the process with ss/netstat.
Is port 587 TCP or UDP?
The registered protocol on this page is TCP. The same number behaves independently on each protocol: TCP may be listening while UDP is idle, so check them separately.
How do I check if port 587 is in use?
On Linux: sudo ss -tlnp 'sport = :587' for an exact port match. On macOS: sudo lsof -nP -iTCP:587 -sTCP:LISTEN. On Windows PowerShell: Get-NetTCPConnection -LocalPort 587 -State Listen. A listener counts as confirmed only when you can see the bind address and process name; without root/admin you will not see other users' processes.
Is port 587 secure? Should I open it in my firewall?
A port number has no inherent security — it depends on whether the listening service is correctly configured and whether it needs exposure at all. Keep loopback/internal-only services firewalled; where public access is required, pair it with source restrictions, VPN or authentication. The caution section on this page lists port-specific risks.
En bref
- Port
- 587
- Protocole
- TCP
- Catégories
- E-mail et messagerie
- État d’utilisation
- 3 logiciels utilisant ce port
Ports associés
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