Anti-Spam SMTP Proxy

{{Infobox software

| name = Anti-Spam SMTP Proxy

| logo =

| screenshot =

| caption =

| author = [http://sourceforge.net/users/jhanna777/ John Hanna]

| developer = [http://www.thockar.com/assp-home Thomas Eckardt] in association with the ASSP community

| latest_release_version = [http://sourceforge.net/projects/assp/files/ 2.8.1(23131)]

| latest_release_date = {{Start date and age|2023|05|11}}

| latest_preview_version = 2.8.2(23136)

| latest_preview_date = {{Start date and age|2023|05|16}}

| operating_system = Cross-platform

| programming_language = Perl

| website = [http://assp.sourceforge.net assp.sourceforge.net]

}}

The Anti-Spam SMTP Proxy (ASSP) is an open-source, Perl based, platform-independent transparent SMTP proxy server.

Features

Some ASSP's features are:

Hidden Markov Model spam filtering
Bayesian spam filtering
whitelisting
Penalty Box (PB) trapping
DNSBL/RBL (Realtime Blackhole Listing)
URIBL (Uniform Resource Identifier Black Listing)
Multi-level SPF (Sender Policy Framework) validation and blocking
DKIM signing and validation
DMARC validation and reporting
SRS (Sender Rewriting Scheme) fix-up
Session Delaying/Greylisting and connection response delaying
Sender validation and recipient validation
Multi-level attachment blocking (based on block lists or allow lists or content based executable blocking)
As well as multiple RFC validation mechanisms.
Multi-threaded (Since version 2.x)
Platform independent (Written in Perl)