Self-hosted email engine.
Self-hosted email infrastructure with 3-pane inbox, server-side rules, and team shared mailboxes. Free @calistopro.com address or custom domain with authentication provisioning in four steps.
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infrastructure layers (engine, auth, outbox, CDN)
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system folders + unlimited custom
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condition fields in the rules engine
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rule actions (move, label, archive, delete, forward)
4 infrastructure layers. Outbound delivery, inbound sync.
Self-hosted email engine on EU infrastructure. Outbound delivery with per-user auth and retry queue. Inbound sync at 60-second intervals. Domain authentication auto-configured per domain.
Self-Hosted Email Engine
EU infrastructure. Per-user auth on outbound.
Deliverability Stack
Authentication key generation. Records auto-configured.
Outbox Retry Queue
Exponential backoff: 30s, 60s, 120s. Three attempts.
Storage & Attachments
25 MB max. CDN delivery with signed URLs.
Maintenance schedule Q3
Outbound delivery. Inbound sync. One engine handles both.
Per-user authentication on outbound with a database-backed retry queue. 60-second inbound sync polling with attachment routing to CDN.
To/CC/BCC. 25 MB attachments. 8 keyboard shortcuts.
Full compose form with signature auto-insertion and draft auto-save. Threaded conversations with dual thread-ID resolution. Full-text search across subject, sender, recipient, and attachment filters.
Keyboard shortcuts: c compose, j/k navigate, e archive, # trash, r reply, / search. Channel badges identify mailbox platform per message. Thread identity resolved via inbound sync thread ID or X-Calisto-Thread-Id header for cross-platform stitching.
6 system folders. Unlimited custom. Color-coded labels.
Inbox, Sent, Drafts, Archive, Spam, Trash built in. Custom folders with unread counts. Labels with color picker for cross-folder tagging. Snooze to resurface messages at a chosen time.
Custom Folders
Unlimited folders beyond the six system defaults. Each tracks its own unread count.
Color-Coded Labels
Create labels with color picker. Apply multiple labels per message. Filter by label.
Snooze
Snooze until a chosen date and time. Cancel snooze to return the message immediately.
,0, MB
max attachment size (CDN delivery)
,0, GB
storage per paid mailbox
,0,s
inbound sync interval
,0,h
auto-reply deduplication window
Server-side rules. Shared mailboxes. Per-mailbox signatures.
Rules evaluate at inbound before messages reach the inbox. Team mailboxes share one address across multiple members.
3 condition fields. 5 actions. Evaluated at inbound.
Rules execute server-side before messages reach the inbox. Condition builder matches From, Subject, and To with contains, equals, and startsWith operators. Priority ordering determines execution sequence. Toggle rules on and off without deleting.
Actions route, label, archive, delete, or forward matching messages. Auto-reply with schedule-based activation and 24-hour per-sender deduplication prevents reply loops.
Shared inboxes. Per-mailbox settings. Member management.
Create shared team mailboxes with their own addresses. Add members who access the shared inbox alongside personal mail. Independent settings per mailbox: display name, signature, auto-reply, forwarding, storage quota.
maria@resort-alma.com
james@resort-alma.com
sara@resort-alma.com
Create Team Mailbox
Provision a shared mailbox with its own address. Multi-step form: name, domain, initial members.
Member Management
Add and remove members per mailbox. Each member accesses the shared inbox alongside personal mail.
Per-Mailbox Settings
Display name, signature, auto-reply, and forwarding configured independently per team mailbox.
Search & Filter
Search all team mailboxes by name or address. Filter by storage quota, platform, and tier.
HTML editor. Per-mailbox. Auto-inserted on compose.
HTML signature editor with formatting toolbar: bold, italic, links, and image embeds. Each personal and team mailbox maintains its own signature and display name. Auto-insert on compose.
Maria Chen
Operations Manager, Resort Alma
+1 (555) 234-5678
resort-alma.com
Formatting toolbar with bold, italic, underline, link insertion, image embedding, and HTML source view. Each personal and team mailbox stores its own signature with display name. Signatures auto-insert when composing new messages or replies.
Four steps. Free or custom domain. Authentication from step one.
Choose free @calistopro.com or custom domain. Authentication keys and records auto-configured during provisioning.
4 steps. Free or custom domain. Authentication from step one.
The setup wizard provisions a mailbox in four steps. Choose free @calistopro.com or custom domain. Authentication keys and records auto-configured during provisioning. Mailbox active immediately.
Choose Domain Type
Free @calistopro.com or custom domain from Sites.
Configure Address
Pick local-part for free domain or select verified custom domain.
Provision Mailbox
Mailbox created cluster-side. Authentication keys generated. Records auto-configured.
Display Credentials
Outbound credentials displayed. Mailbox active immediately for send and receive.
Configure Address
Choose your email address for the selected domain.
Free Tier
you@calistopro.com
Custom Domain
you@yourdomain.com
High-Performance Ops. Zero Monthly Overhead.
Get all 15 Core modules at no monthly cost. You only pay 2% of processed revenue.