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Port 220 (imap3)

IANA assigns port 220 to imap3: Interactive Mail Access Protocol v3.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
imap3 TCP Interactive Mail Access Protocol v3 James Rice -
imap3 UDP Interactive Mail Access Protocol v3 James Rice -

Check what is listening on port 220

Linux: is anything listening on TCP 220?
sudo ss -tlnp 'sport = :220'
Linux: UDP 220
sudo ss -ulnp 'sport = :220'
Linux / macOS: which process owns the port
sudo lsof -nP -i :220
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':220 '
Windows (Command Prompt)
netstat -ano | findstr :220
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 220 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 220
From Windows
Test-NetConnection HOST -Port 220
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 220

Block port 220 in the firewall

ufw
sudo ufw deny 220/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 220 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 220 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 220' -Direction Inbound -Protocol TCP -LocalPort 220 -Action Block
ufw
sudo ufw deny 220/udp
iptables
sudo iptables -A INPUT -p udp --dport 220 -j DROP
nftables
sudo nft add rule inet filter input udp dport 220 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 220' -Direction Inbound -Protocol UDP -LocalPort 220 -Action Block

Related ports

218mpp219uarps221fln-spx222rsh-spx

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.