포트587— SMTP submission / STARTTLS
포트 587은 주로 메일 클라이언트가 제공업체에 메시지를 제출할 때 사용합니다. 포트 25의 서버 간 중계와 구분하세요.
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Configuration and troubleshooting
제공업체가 요구하는 STARTTLS 및 인증 설정을 사용하세요. STARTTLS는 465의 암시적 TLS와 달리 기존 SMTP 세션을 암호화하도록 전환합니다.
Important limitations
포트 번호가 암호화를 강제하지는 않습니다. TLS 협상이 실패하면 평문 비밀번호 전송으로 전환하지 말고 설정을 수정하세요.
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.
이 포트를 사용하는 소프트웨어 (3 개 소프트웨어)
Community software entries: links are references, not individual verification.
사용 시 참고 사항
- 포트 587 사용 전에 다른 서비스가 점유하고 있지 않은지 확인해 주세요
- 포트 충돌이 발생하면 다른 포트를 사용하거나 해당 포트를 점유한 서비스를 중지하는 것을 고려해 보세요
자주 묻는 질문
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.