Description

episode 26: Email protocols with Mauro De Gennaro from Stalwart Labs.

This episode features an in depth conversation with Mauro De Gennaro of Stalwart Labs that demystifies how email actually works in practice, from SMTP delivery and DNS based routing to IMAP, JMAP, spam filtering, encryption, and authentication standards like DKIM, SPF, and DMARC, all through the lens of building and operating a modern mail and collaboration server in Rust; Mauro shares his long personal journey from early BBS systems to founding Stalwart, explains why email protocols have evolved the way they have, how self hosting email can be practical and secure today, and why open standards, automation, and memory safety are key to reclaiming control over critical communication infrastructure.

Learn more:

• https://stalw.art — Website
• https://github.com/stalwartlabs — GitHub org
• https://github.com/stalwartlabs/stalwart — GitHub repository
• https://stalw.art/docs — Documentation (including installation instructions)
• https://stalw.art/slides — Product presentation slides
• https://fosdem.org/2026/schedule/event/FP8EFX-scaling-email/ — FOSDEM 2026 talk
• https://www.ietf.org/meeting/125/ — IETF 125 Shenzen

Rama

If you like this podcast you might also like our modular network framework in Rust: https://ramaproxy.org

Chapters

• 00:00 Intro
• 00:50 Get to know Mauro De Gennaro
• 08:44 Origins of Stalwart
• 12:24 The Evolution of Stalwart and Its Features
• 14:59 Life of a mail sent to a Stalwart server
• 18:14 Understanding Email Transmission and Protocols
• 22:54 Combination of Email with Calendar and Contacts
• 26:37 Email File Attachments
• 31:56 Stalwart and ACME
• 39:44 Email Address validation
• 44:47 Exploring the Sieve Protocol for Mail Filtering
• 47:54 Email RFCs and standarization
• 54:39 Experiences at FOSDEM and the Future of Email
• 56:50 The Case for Self-Hosting Email Solutions
• 01:00:27 Backup Strategies for Self-Hosted Email Servers
• 01:04:35 Ensuring Redundancy and Reliability in Email Hosting
• 01:12:38 Comparing Email Protocols: SMTP, POP3, and IMAP
• 01:16:25 Shared Inboxes and Automated Email
• 01:24:26 Understanding Email Authentication Standards
• 01:27:54 ARC, SPF, DKIM and DMARC
• 01:33:24 Integrating AI with Email Systems
• 01:36:03 Self-Hosting Considerations
• 01:39:31 Getting Started with Stalwart
• 01:41:54 Outro

Netstack.FM

• More information: https://netstack.fm/#episode-26
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Music for this episode was composed by Dj Mailbox. Listen to his music at https://on.soundcloud.com/4MRyPSNj8FZoVGpytj