A transfer moves a domain from one registrar to another. The domain itself does not change, the website does not go down, and mail keeps arriving throughout, because a transfer changes who administers the name rather than where it points.
It is worth knowing that most registries charge a transfer as though it were a renewal, and the domain normally gains a year in the process.
The three things that have to be true
Almost every failed transfer fails on one of these, and all three are checkable in advance.
The domain is not locked. A registrar lock exists to stop a domain being moved without your involvement, and while it is on, a transfer is refused. It has to be turned off first, and locking and unlocking is covered in locking and unlocking a domain.
You can get the transfer code. The registry wants proof that you are entitled to move the name, and it takes the form of a code the current registrar issues. Some registrars call it an EPP code, some an auth code, and the toolbox calls it a Transfer code.
The domain is old enough. Most registries refuse a transfer within a short window after a registration or a previous transfer, usually sixty days. That is a registry rule with no way around it, and the only answer is to wait.
Getting the code from your current registrar
This happens at the registrar you are leaving, not here. Most issue the code from their control panel, and it is usually displayed once and emailed to the registrant contact rather than stored where you can read it again later.
If the domain is already with us and you are moving it out, the toolbox issues it for you. On the Domains page each row has a key icon labeled Request transfer code, and the same control appears on the domain's own page.
What happens next depends on the registry. Some domains return the code directly, and the toolbox shows it to you. Others accept the request and then email the code to the registrant contact, so it arrives as a message rather than on screen — and a few extensions need no code at all, which is true of .co.za and is covered in transferring a .co.za domain.
Starting the transfer
Once the domain is unlocked and you have the code, the transfer is ordered from the toolbox with the domain name and the code. Nothing about the domain is disturbed while it is pending.
The losing registrar is notified and may send a confirmation you have to approve. If it does and you miss it, the transfer simply times out, and nothing is lost — you start it again.
Do not cancel the old service yet
The single most common way to lose a domain is to cancel its old registration before the transfer has completed. Until the transfer finishes, the old registrar is still the registrar, and cancelling the service there can leave the domain in a state nobody can move.
Wait until the domain appears in the toolbox as active, and until a DNS lookup shows it resolving the way you expect. Then let the old service lapse on its own.
One thing that arrives afterwards
A transfer in is one of the events that can trigger registrant email verification, which is a registry requirement rather than ours. It is a single email to the domain owner's address with a link to click, and ignoring it eventually suspends the domain. It is a single email with a link to click, it takes a moment, and ignoring it eventually suspends the domain.
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