[Report tool · mail migration]

Stalwart migration calculator

A mail migration touches identity, mailboxes, calendars, contacts, devices, DNS, security, and habits. Use this estimate to find the work that needs a pilot before cutover.

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[Assumptions]

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Every field is editable. The result is a decision aid, not a quote.

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Report tool · mail migration

Stalwart migration calculator

Medium friction at this mail environment size

Plan around 134 hours of migration, pilot, validation, and coexistence work before retiring the old system.

Entered assumptions

Current mail system
Microsoft 365 or Exchange
User mailboxes
50
Shared mailboxes or groups
8
Users with calendars or contacts
30
Mail-connected systems
6
Retention and compliance need
Medium
Migration hours per mailbox
0.8
Delivery or internal rate / hour
$120.00
Stalwart infrastructure / month
$350.00
Coexistence or pilot weeks
4
Estimated work134 hoursMigration, testing, and coexistence
Transition estimate$16,406Uses your delivery rate and infra input
Mailboxes508 shared or group addresses
FrictionMedium friction · 67%Workflow complexity signal
Pilot window4 weeksEdit to match your change calendar

Where friction usually appears

Mail can look simple until a team relies on every edge around it.

  • Login names, aliases, groups, shared mailboxes, and permissions
  • Calendars, contacts, filters, flags, folders, and stored files
  • Mobile clients, desktop profiles, scanners, alerts, and application relays
  • MX, SPF, DKIM, DMARC, DNS timing, spam handling, and delivery reputation
  • Retention, legal hold, recovery, support ownership, and rollback

A safer shape for the move

Start with a pilot and keep the old service available. Move a few accounts, validate every data type, watch delivery, and only then increase the batch. A reversible account-by-account move is easier to reason about than one large cutover.

Recommended next step

Run a technical pilot with a shared mailbox, a calendar-heavy user, an application relay, and a rollback drill before setting a cutover date.

Read the caveat

Stalwart provides migration tooling, but your source data, identity setup, DNS, devices, contracts, and operating capability still determine the real effort.

Prepared with TWN Systemstwn.systems

[Sources and context]

Use the official sources below to replace indicative assumptions with current terms, limits, and operating guidance.