whatportis.com
suggest an edit →

Port 783SpamAssassin spamd

SpamAssassin's spamd daemon listens on port 783 to perform content-based email filtering, identifying spam through a vast array of heuristic and signature-based tests. Designed to work alongside mail transfer agents, spamd enables rapid analysis of inbound mail streams, efficiently tagging or rejecting unwanted messages. It is a popular tool integrated into many email security solutions to reduce spam volume and protect users from unsolicited messages and common email threats..

inEmailSecurityNetwork Services
transport
tcp

single transport

in transit
cleartext

payload readable on path

assignment
unofficial

used by convention

risk
4/10

caution

lookups
6,048

rank 822 of 993 · top 83%

Technical Details

what runs on :783

SpamAssassin’s spamd is a lightweight, daemonized server component of the Apache SpamAssassin project. It listens on port 783, typically over TCP, providing a fast network-based API to analyze email content for spam characteristics. Rather than invoking SpamAssassin’s full Perl process per message, spamd optimizes system performance by maintaining a persistent service, greatly reducing resource utilization.

The communication primarily follows the spamc/spamd protocol, enabling email systems to submit mail messages for scoring. The client, spamc, connects via TCP port 783 and streams mail content; spamd then evaluates the content against a wide array of rules, Bayesian filters, and network-based tests (like RBLs and URL reputation). The results include a spam score and optional modification of message headers with spam-related metadata.

While it typically runs on email gateways or mail servers, spamd can be configured for local or distributed deployments, scaling from single-server installations to complex, clustered environments. Port 783’s role is thus crucial in enabling fast, asynchronous filtering operations within the broader email infrastructure.

Security Information

exposure of :783

risk score

4/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

email averages 3.9 across 42 ports — this one sits 0.1 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

unofficial

used by convention, not registered — what answers here varies by deployment

reachable over

tcp

every listening transport is another surface to filter at the edge

security overview

Common Vulnerabilities:

  • Lack of encryption makes unprotected traffic between spamd and spamc vulnerable to interception or tampering.
  • If exposed externally, attackers may exploit spamd port access for unauthorized spam scoring requests, denial-of-service (DoS), or as an entry vector.
  • Outdated SpamAssassin versions can be susceptible to remote code execution, or bypass techniques allowing spam to evade detection.

Common Mitigations:

  • Always deploy spamd behind internal firewalls, restricting port 783 to trusted mail servers.
  • Use secure tunnels (e.g., SSH, VPN) or stunnel wrappers to encrypt communication if spamd must be accessed remotely.
  • Regularly patch SpamAssassin to mitigate known vulnerabilities.
  • Implement network monitoring on port 783 traffic to detect abnormal or unauthorized access attempts.
  • Employ proper access controls and limit spamd privileges on the host system to reduce potential impact if compromised.

Related Ports

all 42 in email →

the 8 most looked-up other ports in email — 42 ports carry that label.

portservicerisk
:143IMAPcaution
:995POP3Scaution
:109POP2caution
:2096cPanel SSL Webmailsafe
:110POP3caution
:993IMAPScaution
:1352Lotus Notes RPCcaution
:24Private Mailcaution

risk mix of the 8 listed

  • safe13%
  • caution88%

3 of 8 encrypted