hMailServer to Office 365 Email Migration
hMailServer is an email server that supports SMTP, IMAP, and POP3. For this EdbMails workflow, hMailServer is treated as an IMAP email source, so the migration scope is supported messages, attachments, mail folders, folder hierarchy, and common message properties exposed by the server.
Because hMailServer is self-hosted, the IMAP host name, listener ports, TLS certificates, authentication settings, firewall rules, and external reachability are administrator-defined. Verify the production configuration before migration instead of assuming one hostname or security mode.
The EdbMails IMAP Migration Tool supports single/bulk mailbox connection, source-to-target mapping, selective migration, concurrent processing, incremental follow-up runs, pause/resume, and migration reports.
The Microsoft 365 target uses the current EdbMails OAuth-based connection workflow. Standard IMAP does not migrate hMailServer server settings, aliases, distribution lists, rules, contacts, calendars, or other non-mail configuration.
Use this provider-specific guide together with the main IMAP to Office 365 migration page.
User Query
“We are currently running hMailServer on Windows and would like to migrate our business emails to Office 365 now that our team has grown. We are looking for a suitable method or approach to safely migrate our data without leaving any loose ends. Could anyone please assist us step-by-step? Thanks for the guidance”
hMailServer email to Office 365 Migration Plan
- Inventory hMailServer domains, user mailboxes, mailbox sizes, folder counts, aliases, and active accounts.
- Confirm the externally reachable IMAP server name, port, TLS mode, and authentication credentials for each source mailbox.
- Identify non-IMAP configuration such as aliases, routes, rules, distribution lists, and server settings that must be recreated separately if still needed.
- Create/provision Microsoft 365 target users/mailboxes and assign the required licenses.
- Add and verify the custom domain if it will be retained after cutover.
- Check source connection limits, firewall/NAT rules, Microsoft 365 throttling, message-size limits, and available bandwidth.
- Run a pilot mailbox before production migration and plan incremental follow-up passes before changing MX/DNS.
Pre Migration Activities for hMailServer to Office 365 Migration
- Confirm the hMailServer IMAP service is enabled and reachable from the EdbMails computer.
- Verify the source host name, configured IMAP port, TLS/SSL mode, certificate, username format, and mailbox credentials. Secure IMAP commonly uses port 993, but hMailServer port bindings are administrator-configurable.
- For bulk migration, prepare the EdbMails sample CSV and test a small representative set first.
- Create/provision the target Microsoft 365 mailboxes and assign licenses.
- Add and verify the custom domain if Microsoft 365 will receive production mail for it.
- Use the current EdbMails OAuth-based Microsoft 365 target connection and review target throttling/message-size limits.
- To connect a single hMailServer mailbox, select ‘Single User / Account Migration’, choose ‘Connect to IMAP Server’, and click ‘Next’.
hMailServer to Office 365 Post Migration Tasks
Step 1: Update the MX records to point to Office 365
If you have not done this step previously, change the DNS records known as MX records to enable email and receive messages on the target Office 365 server. In addition, configure the Autodiscover record to allow Outlook to connect to the migrated mailboxes.
Step 2: Create a new Outlook profile for users in the new domain
Configure the Outlook profile for each user in your domain if Outlook has problems connecting to Office 365 mailboxes.
Troubleshooting Guide for hMailServer to Office 365 Migration
Explore the knowledge base articles for troubleshooting common issues. For more information on EdbMails IMAP migration, review the FAQs or contact our dedicated support team for assistance.
Benefits of EdbMails for hMailServer to Office 365 Email Migration
- Bulk mailbox migration
Prepare multiple hMailServer accounts through CSV and process migration batches without entering every account manually.
- Selective email migration
Select required mailboxes/folders and use supported filters for subject, sender/recipient, date range, attachments, and folder exclusions where applicable.
- Incremental follow-up runs
Process eligible new or changed email items after the initial pass to support staged migration before cutover.
- Preserve supported email structure
EdbMails is designed to retain supported folder hierarchy, messages, attachments, and common message properties exposed through hMailServer IMAP.
- Mailbox mapping and reports
Review automatic/manual mappings and use migration reports plus target-side verification before retiring the source mail system.
