Self-hosted apps that integrate with SMTP email servers

5 open-source, self-hostable projects list SMTP email servers as an integration.

• TwentySelf-hosted, open-source CRM platform for technical teams to build custom solutions with AI agents, workflows, and extensible data models.
• indicoSelf-hosted, open-source event management system from CERN for conferences, meetings and lectures: abstracts, registrations, timetables, badges and room booking.
• TailchatSelf-hosted open-source IM platform with plugin system, microservices, panels, RBAC, bots, OAuth, voice/video calls.
• ackifySelf-hosted platform for cryptographic proof of document reading via Ed25519 signatures. Supports OAuth2 and MagicLink for compliance and GDPR.
• OpenOlitorOpenOlitor is a self-hosted, open-source platform for CSA groups to manage members, deliveries, invoicing, and a member portal under AGPL-3.0.