Email protocols with Mauro De Gennaro from Stalwart Labs

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 Join our Discord: https://discord.gg/29EetaSYCD Reach out to us: [email protected]

Music for this episode was composed by Dj Mailbox. Listen to his music at https://on.soundcloud.com/4MRyPSNj8FZoVGpytj