Fiddler - Fiddler is a debugging program for websites.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
HTTP Toolkit - Beautiful, cross-platform & open-source tools to debug, test & build with HTTP(S). One-click setup for browsers, servers, Android, CLI tools, scripts and more.
Proxmox Mail Gateway - Protect mail server against spam, viruses and malware with Proxmox Mail Gateway security for businesses, government, education and non-profit organizations.