Introduction
Many Thai and Singapore SMEs still run mail on shared hosting (cPanel), ISP mailboxes, or legacy POP/IMAP accounts. Moving to Microsoft 365 gives you Exchange Online, Teams, and proper mobile sync — but you must migrate mailboxes and switch DNS without losing messages.
When POP/IMAP migration fits
| Scenario | Approach |
|---|---|
| Few users, small mailboxes | Manual IMAP migration in Outlook or admin tools |
| 5–50 users, years of mail | Staged migration with migration endpoint |
| Google Workspace | Use Google migration guide instead |
| On-prem Exchange | Cutover or hybrid (partner-led) |
This article focuses on hosted IMAP (typical of local web hosts).
Phase 1 — Prepare Microsoft 365
- Buy or assign licenses (Business Standard is the usual minimum for desktop Office + mail).
- Add and verify your domain.
- Create mail-enabled users in admin center matching source addresses (or aliases you will keep).
Phase 2 — Migration batch
In Exchange admin center → Migration:
- Choose IMAP migration
- Enter source server host, port (993 SSL typical), and credentials per mailbox
- Start with a pilot mailbox (IT admin) before the whole company
Microsoft copies folders into Exchange Online. Large PST archives may need separate import.
Phase 3 — Sync period
Run migration while old MX still delivers to the old host or use dual delivery if your host supports it. Give 24–72 hours for initial sync; delta sync picks up new mail until cutover.
Phase 4 — DNS cutover
On a planned evening or weekend:
- Confirm migration sync 100% complete for all users
- Update MX to Microsoft (see custom domain guide)
- Update Autodiscover CNAME if prompted
- Send test mail in and out from Outlook and mobile
Rollback plan: keep old MX TTL low (300s) for 48 hours if possible.
Phase 5 — Client reconfiguration
Users should:
- Remove old IMAP profiles from phones (avoid duplicate drafts)
- Set up Outlook or Outlook mobile with Microsoft 365 account
- Re-download calendars and contacts from Exchange (not local PST-only stores)
Licensing and cost (reference)
| Plan | Thailand | Singapore |
|---|---|---|
| Business Basic | S$18 | S$18 |
| Business Standard | S$26 | S$26 |
See full pricing. Migration labour is separate — we quote based on mailbox count.
Risks to plan for
- Sent items not on IMAP — may not migrate; export PST if critical
- Large attachments — extend sync window
- Shared mailboxes — create as shared mailbox or group, migrate separately