- Require TLS and authenticated submission.
- Make sure the server is not an open relay.
- Publish SPF, DKIM and DMARC for the domain.
Port 3332: MCS Mail Server
Port 3332 is assigned by IANA to mcs-mailsvr (MCS Mail Server).
3332
How mcs-mailsvr works
EmailMail servers hand messages to each other over port 3332, one hop at a time, until the recipient's server.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Registered (1024-49151)
- Category
Is port 3332 dangerous?
We have no specific security note for port 3332. Its risk depends on the program actually listening on it. General advice for email services:
IANA registry entries for port 3332
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| mcs-mailsvr | 3332 | TCP, UDP | MCS Mail Server | - | - |
// source: IANA service name and port number registry
Which program uses port 3332, and is it reachable?
Linux
sudo ss -ltnup 'sport = :3332' # process listening on 3332
sudo lsof -nP -i :3332macOS
sudo lsof -nP -i :3332
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3332 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 3332 netstat -ano | findstr :3332
From another machine
nmap -p 3332 -sV <host> sudo nmap -sU -p 3332 <host> nc -zv <host> 3332
Block it in the firewall
sudo ufw deny 3332/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 3332" -Direction Inbound -LocalPort 3332 -Protocol TCP -Action Block # Windows
What is port 3332 used for?
Port 3332 is assigned by IANA to mcs-mailsvr (MCS Mail Server).
Is port 3332 TCP or UDP?
Port 3332 is registered for TCP and UDP.
Is it safe to open port 3332?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Require TLS and authenticated submission.
How do I check if port 3332 is open?
On Linux run "ss -ltnup 'sport = :3332'", on macOS "lsof -nP -i :3332", and on Windows "netstat -ano | findstr :3332" to see the local process. From another machine, "nmap -p 3332 <host>" shows whether it is reachable.