imapsync

imapsync is an IMAP mailbox transfer tool for migration and backup, with a command-line program and an online sync service. It suits administrators and individual users moving mail between IMAP accounts who value resumable transfers over a broader collaboration-data migration suite. Its focused transfer model is practical, but limits on calendars, contacts, two-way sync and local directories rule it out for some moves.

Overview

Founded in 2001, imapsync is authored by Gilles Lamiral in Baulon, France. Its core job is moving or backing up mail between IMAP accounts. The command-line tool transfers incrementally and recursively; if a job stops, it can be restarted without creating duplicates. That makes it a sensible fit for migrations that may need to run in stages or recover from interruption.

The maker lists compatibility with services and server software including Gmail, Office 365, Exchange, Dovecot and Zimbra. Tenant-to-tenant and staged migrations are supported, as are Microsoft 365, Google Workspace and IMAP. But imapsync handles mail, not a complete account: it cannot migrate contacts or calendars, keep two active accounts synchronized in both directions, or transfer messages to or from a local directory.

Key features

Resumable mailbox transfers

Incremental, recursive transfers and duplicate-safe restarts are the standout strengths. They make imapsync useful for large or staged mailbox moves where an interrupted run should not mean starting over. This is still a one-way transfer tool rather than a way to maintain two live mailboxes in sync.

Command line, online sync and self-hosting

The command-line software runs on Windows, Mac OS X and Linux. The online service allows free mailbox syncs below 3 GB; purchases enable unlimited syncs of any size. Buyers also get a visual interface for installation on a Linux server, but it does not yet work on Windows. The service’s privacy policy says it may collect email addresses, cookies, usage data and diagnostic information, and cannot guarantee absolute data security, a consideration for organizations with strict data-handling requirements.

Pricing

imapsync is freemium, with a free online option for syncs below 3 GB. There is no free trial; purchases have a 30-day money-back guarantee. The one-time plans are:

• Software only — €72, paid once: Windows, Linux and Mac OS X software, lifetime updates and unlimited use. Best for users who can manage transfers themselves and do not need developer support.
• Professional support — €144, paid once: migration-work support from the developer. Paid professional support is in English, mostly by email, with phone or Skype possible during stated office hours of 10:00–16:00 UTC. This suits users who want help with migration work rather than just the software.
• Imapsync + support — €144, paid once: software, professional support, unlimited online syncs and lifetime updates. At the same price as support alone, it is the fuller option for buyers who want both the tool and online capacity beyond the free cap.

The free option is constrained by the 3 GB online-sync limit; buying removes the size limit and permits unlimited syncs. A 30-day refund period offers recourse, but it is not a substitute for a trial.

Platforms

imapsync supports Linux, macOS and Windows, alongside web access and self-hosting. The command-line software runs on all three desktop operating systems; the buyer visual interface is for Linux servers, not Windows. That split matters: Windows users can run the command-line tool, but cannot host the visual interface there.

Who it's for

Choose imapsync for IMAP mailbox migration or backup, including staged and tenant-to-tenant moves, when resumable transfers and duplicate-safe restarts are useful. It is especially suited to technically comfortable users who can work with command-line software, or buyers who want Linux self-hosting or developer migration support. Look elsewhere if the project includes calendar or contact data, local-directory transfers, or ongoing two-way synchronization.

Pros and cons

• Pro: Transfers can be stopped and restarted without generating duplicates, reducing the risk of repeating an interrupted migration from scratch.
• Pro: Incremental, recursive transfer and support for major IMAP services and server software suit mailbox moves across varied environments.
• Pro: The free online option handles syncs below 3 GB, while paid plans allow unlimited syncs of any size.
• Con: It does not migrate contacts or calendars, so it cannot by itself move all account data.
• Con: It does not provide two-way synchronization or local-directory transfers, limiting it to mailbox-to-mailbox transfer use cases.
• Con: The visual self-hosted interface is limited to Linux servers, and online use comes with stated collection of usage and diagnostic data and no guarantee of absolute security.

Alternatives

For a broader comparison, browse Email Migration Software. Consider CloudM Migrate if you need its Google Workspace Shared Drives and public-folder migration with permissions, folder structure and version history. MigrationWiz is a paid alternative with a free trial and a per-user Mailbox plan at $14, paid once, covering up to 50 GB. Cloudiway Mailbox Migration Tool offers a free trial and a Standard plan at $570, paid once for 50 migration licenses and one workload.

SysTools Email Migration Tool is another option, with a free demo for up to two user accounts and a paid version at $35, paid once for five users. CodeTwo Office 365 Migration may suit a Windows or self-hosted Office 365 migration; its one-off price depends on mailbox count and currency, with a 10-mailbox minimum. CodeTwo Exchange Migration is a Windows and self-hosted Exchange migration option with a one-off license and support that expires after one year. For a free mailbox tool across desktop and mobile platforms, MailJerry offers unlimited mailboxes at 150 MB each, up to three simultaneous migrations and use on one device. Zoho Mail is a broader mail service with a forever-free plan for five users, one domain and 5 GB of storage per user.

Verdict

imapsync is a strong choice for users who need focused, resumable IMAP transfers and can work within a mail-only scope. Its duplicate-safe restarts, staged-migration support and straightforward one-time software price make it easy to recommend for mailbox moves. Choose another tool if contacts, calendars, two-way sync or local-directory transfers are essential, or if Windows self-hosting of the visual interface is required.