Switch providers without your company going without email

The list of accounts, the password for each mailbox at the current provider and the address of the source IMAP server. The copy is done mailbox by mailbox, so no administrator credentials for the previous provider are needed.

This information does not pass through anyone. Each company has its own administrator account in the INBOX admin panel, and it is the company's administrator who enters the source credentials there. Passwords are not sent by email, message or ticket, and are not held by a technician.

Source passwords are stored encrypted and used only for the copy. The panel never displays them: the administrator can set or replace a password, but never read it back.

If the source provider requires two-step verification, the password used is an app password generated with that provider.

The migration can be handled by the Horizon team, at no extra cost, or run by the domain administrator in the Migration section of the admin panel. The tool is the same and offers two paths.

In bulk, to move the whole company at once. The administrator uploads a CSV file with the accounts, and the panel provides a ready-made template to download. The file has a header row and three required columns — usuario, senha and imap_host (username, password and IMAP host) — plus two optional ones, imap_port (993 by default) and ssl. It is comma-separated, UTF-8 encoded, and the columns can be in any order as long as the names match. Each file can hold up to one thousand accounts.

Individually, one mailbox at a time. The administrator enters the destination mailbox, the source login and password, and the IMAP server; the port is detected automatically. Before starting, the connection test shows the port, the security mode, how many messages there are and which folders were found.

Both paths follow the same sequence: the new mailboxes are created, the entire archive is copied with the folder structure preserved, the copy keeps running incrementally while the old email stays active and, once DNS has been switched over, a final pass is made. Messages are compared one by one, so nothing is duplicated.

The panel shows each account with its status, percentage complete, how many messages have been copied and the copy throughput, and flags the ones that failed — for example, an incorrect source password.

There is also a check that compares source and destination folder by folder and points out anything missing.

An account with a problem is fixed on its own: you can correct the password for that mailbox and sync again, without re-uploading the file and without redoing the others.

Only that row is marked as an error; the rest proceed normally. Before importing, the panel validates the file and shows, row by row, what is correct, what needs attention and what is wrong.

The whole file is rejected only for a structural problem: a required column missing from the header, an empty file, more than one thousand rows or a size over 1 MB.

No. The old email works the whole time and nothing is deleted at the source. The copy runs in the background, with several mailboxes in parallel.

DNS is switched over when the company decides, after the bulk of the archive has been copied. The time required depends on the volume in gigabytes, the number of accounts and the source provider's speed limits, so we do not work with a fixed timeframe — it can take hours or days, depending on the case.

They are recovered. Before wrapping up, the sync runs once more and brings in whatever reached the old account in the meantime, comparing messages one by one to avoid duplicates.

The automatic migration covers email messages. Contacts and calendar events are not included.

Contacts have a manual path. Each user exports their contacts from the old provider as vCard (a .vcf file) and imports them into the new mailbox, through the webmail or the Android app, without depending on the administrator or support. A single file with many contacts is imported in one go.

The import preserves name, primary email, phone number, company and notes. Additional emails and phone numbers, job title, address, photo and birthday are not imported, and contacts without an email address are skipped.

Calendar events have no file import path and need to be recreated.

For messages, read/unread status and star flags are not preserved: messages arrive marked as read. Folders, attachments and the original date of each message are kept.

From any provider that offers password-based IMAP access, which covers most of the market.

Gmail and Google Workspace accounts work, using an app password.

Microsoft 365 accounts where IMAP has been disabled by the administrator cannot be included in the automatic migration, because in that case access is only possible through modern authentication. A manual path remains: each user imports messages into the new mailbox from an MBOX or EML file, through the webmail, without depending on the administrator.

An Outlook .pst export must first be converted to MBOX or EML — .pst files are not accepted directly. Through this path, messages arrive with their attachments and original date, but all are marked as read and the folder tree is not recreated.

There are two paths, and the company chooses.

Publishing them yourself. The panel generates ready-to-use MX, SPF, DKIM and DMARC values, with a DKIM key created for the domain, and a checker verifies whether what is published matches what is expected. If any record is wrong, the panel identifies it and generates numbered step-by-step instructions for what to fix at your DNS provider.

Moving your DNS to Horizon. The panel imports the records from your current provider and hosts the entire zone. From then on, you just point the domain to our servers. Email records are protected against accidental removal — you remain free to edit and add your own, such as the TXT record for a bulk-sending tool, but you cannot delete by mistake the ones that keep email working.

Reverse DNS is configured by Horizon on its own address block, without depending on third parties. The DKIM key already generated can be viewed at any time for republishing, with no need to create a new one — generating another would invalidate the signature until it propagates.