Self-hosted · open source (MIT)
Ironbrain MailCal
Email and calendar for agents and scripts—straight against your own IMAP, SMTP, and CalDAV servers, no Gmail or Outlook API required. MailCal comes as a command-line tool and as an MCP server, and both share the same configuration.
Available on nuget.org and as a Cursor plugin on cursor.directory.
Who is MailCal for?
For anyone whose mailboxes and calendars run on their own or rented servers—Mailcow, SOGo, Dovecot, or mox, for example—and who wants agents to work with them without a cloud service in between. Credentials live in a local file on the machine where the agent runs.
What MailCal does
Multiple accounts
Any number of mailboxes and calendars in one file, with a default account. Pick the account per call with -a or an environment variable.
List and read messages, send and reply, move to folders, and archive—into a yearly folder such as Archive/2026 by default.
Calendar
List calendars—including shared and delegated SOGo calendars—query appointments by day or week, and create new appointments.
Per-account send lock
Set "Enabled": false in an account’s SMTP section to make it read-only. Send attempts then fail with a clear error—no other account steps in.
CLI or MCP?
Both read ~/.config/ironbrain/mailcal.json and can do the same things. What matters is how your agent works—and you can install both.
Command line
ironbrain-mailcal
For shell scripts, cron jobs, CI, and agents that run commands. Read commands print JSON you can pipe straight into other tools.
MCP server
ironbrain-mailcal-mcp
For Cursor, Claude, and other MCP clients. The server runs locally over stdio and exposes email and calendar tools right in the chat.
Already using Ironbrain?
MailCal runs actions immediately and has no Outbox. If your organization has an account on app.ironbrain.de, use Ironbrain MCP instead: credentials stay on the server, and critical actions wait for your approval.
Installed in two commands
You need the .NET 10 SDK. The tools come straight from nuget.org.
dotnet tool install -g Ironbrain.MailCal.Cli
dotnet tool install -g Ironbrain.MailCal.McpQuestions or ideas for MailCal?
Report bugs and requests as a GitHub issue—or just send us an email.