Migration runbook · Intermediate · 1–2 hours or a support ticket
How to migrate email to new host — Email Migration Is a Sync Job With a Clock On It
You have to move mail without losing a message, and the only thing between you and a bounce storm is the order you do things in.
The short answer
The order of operations is the job: destination mailboxes first, then an IMAP sync of the history, then the MX cut with both servers still accepting, then a second sync to sweep up whatever landed on the old side while DNS caches expired.
Verification is a count, not a feeling. Record message counts per folder before you start and compare them afterwards; that is the difference between nothing was lost and nothing appears to be missing. Lowering the MX TTL a day ahead is what turns the cut from a wait into a controlled switch.
By the HostingFast team · Reviewed 24 August 2026
Intermediate
Difficulty grade
Quick
Time budget
5
Stages
24/7
Engineer cover
Written for whoever has to do this without downtime. It assumes you can create mailboxes, read an MX record and run a sync tool, and it names the point at which each of those has to happen.
Our engineers will run the whole thing for you at no charge, IMAP history and DNS sequencing included. The runbook is here anyway, because knowing the sequence is what lets you check the work.
The order of operations is the job
Every failure mode in mailbox migration comes from doing two correct things in the wrong sequence. Flip MX before the destination mailboxes exist and the new server rejects mail for accounts it has never heard of — the sender gets a hard failure, not a retry.
So: create the addresses, sync the history, then move MX while the old server is still running. Nothing about that order is negotiable, and nothing else about the job is difficult once it is followed.
Lowering the TTL before you touch anything
Propagation is not a mysterious delay; it is cache expiry. Every resolver holds your MX record for as long as its TTL says, so a record published with a day-long TTL takes up to a day to stop being used, no matter how quickly you change it.
Drop the MX TTL to a few minutes at least one full TTL before the cut. That way the switch itself takes minutes rather than hours, and if something is wrong you can put the old record back and have it honoured almost immediately. Raise the TTL again once the move has settled.
Syncing, and how to prove it landed
An IMAP-to-IMAP sync connects to both servers and mirrors folders, messages, flags and read state. It is the only method that carries the structure across — exporting to files and re-importing loses flags, and dragging folders in a desktop client loses patience.
Before the first pass, write down the message count for every folder on every mailbox. After the final pass, compare. Spot-check the oldest message in the largest folder as well, because a sync that stopped early looks complete until you go looking for 2019.
The client cut-over, and the ports
Once MX has moved and the second sync is done, point the clients at the new server: 993 for IMAP over TLS or 143 with STARTTLS, 465 or 587 for submission, with authentication on. If both hosts use the mail.yourdomain convention, most clients need only a new password.
Keep the old mailboxes alive for a week. Anything that still resolves to the old MX from a stale cache lands there, and a final sync collects it. Deleting the source early is the one way left to actually lose mail.
The platform this migration was rehearsed on
Every step was exercised on the stack we operate — cPanel, the same IMAP service, the same DNS editor — so the sequence described is the sequence your account behaves to.
Backups run daily on every plan, and restoring a file or a database is a single click in the panel rather than a support ticket.
- Sequence stated, not implied
- TTL handled a day early
- Verified by folder counts
- Engineers on shift at any hour
Why HostingFast
Standard on every plan
Order of operations, stated
Destinations, sync, TTL, cut, re-sync — in that order, because reversing any two of them causes bounces.
Counted, not assumed
Folder and message counts before and after are what turn nothing lost into something you can actually show.
The TTL clock handled early
Dropping the MX TTL a day ahead is the difference between a controlled cut and an afternoon of waiting.
Ports and settings printed
993, 143, 465 and 587 with the encryption each expects, so client reconfiguration is not a guessing game.
Overlap instead of downtime
Both servers accept mail through the changeover and the second pass sweeps up whatever the caches delayed.
Or hand it to our engineers
Mailbox migration is included with hosting — the IMAP history sync and the DNS sequencing both.
Quick Start
From order to online
- 1
Inventory folder and message counts
Per mailbox, per folder, written down. Thirty seconds of counting is what makes the verification step at the end mean something.
- 2
Create every destination mailbox first
Same addresses, empty and waiting, on the new server. Nothing else in this runbook may happen before this is finished.
- 3
Drop the MX TTL a day ahead
Set it to a few minutes and wait out at least one old TTL. Propagation after that is cache expiry you have already paid for.
- 4
Run the first IMAP sync
Mirror folders, flags and read state from old to new. Expect the first pass to be the long one; subsequent passes only carry the difference.
- 5
Cut MX with an overlap, then re-sync and verify
Change the MX while the old server still runs, wait out the short TTL, run the sync again, then compare your counts folder by folder.
Built In
Loaded onto every plan
- Mailboxes on your own domain, included with the plan
- IMAP, POP, SMTP and browser webmail on every mailbox
- Migration handled by our engineers at no charge
- Daily backups with restores you trigger yourself from the panel
- Spam and virus screening on every mailbox as standard
- cPanel — the panel most of the industry already automates against
- NVMe SSD storage on every tier, not just the expensive ones
- DDoS filtering absorbed at the network edge
- Renewal billed at the rate you first signed up at
- No setup fee on any plan, ever
Frequently Asked
What people ask us most often
How do I prove nothing was lost?
Compare per-folder message counts from before the move with the counts afterwards, and open the oldest message in the largest folder. A sync that stalled partway through reports success and leaves a gap at the far end of the history, which is exactly where nobody looks.
Do I have to shut the old mailboxes down at cut-over?
No, and you should not. Leave them accepting for about a week: resolvers holding a stale MX record will keep delivering there, and a final sync collects whatever arrived. Deleting the source early is the only reliable way to lose messages in this process.
How quickly can a site be serving traffic from a cold start?
Fast — think minutes rather than days. Your account activates the second payment clears, the domain (free for the first year on annual plans) connects immediately, and the one-click installer has WordPress or any of 240+ applications running before your coffee cools. Got a site somewhere else already? Send us the details and we migrate it free, normally within a day.
What is the uptime target, and what happens if a month misses it?
99.9% — and if a month drops below that because of a fault on our side, our terms entitle you to a pro-rated credit; ask and we apply it. We deliberately call it a target rather than a contractual SLA. Hardware and network faults surface through platform monitoring, usually before the first customer notices anything.
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A straightforward sequence for a switch your visitors never feel: which files move first, how to shift email across without losing a single message, the right moment to repoint DNS, and the two mistakes behind almost all the downtime we get asked to rescue.
Move it once, verify it twice.
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