DNS and MX records query

[Jeep Stone]

We are occasionally asked to swap over clients DNS records when they change hosting. We normally setup the new email addresses on the hosting as well so that they are in place when the MX records switch over. However, as there is always a delay in the DNS records moving (and I'm assuming also MX records) I'm wondering what happens to mail that gets incorrectly sent to the old servers. If seen that you can ask the host to drop the TTL to improve the update speed, but is there anything that can be done with the MX tags to prevent mail loss? This isn't such a problem for small clients who don't get email, but larger clients would surely suffer?

[Jeewhizz]

You should be able to set the old server to just act as a secondary MX for the new server. This would then push the email to the new server as it was received.

You could just set the old server to reject emails for that domain. The sending server should queue the email for 3 days (iirc) and by that time, it'll have the new details.

[Jeep Stone]

When you say reject, do you just mean, delete the MX records?

[Jeewhizz]

No - on the actual server, remove the domain/addresses in question. When the mail is sent to that server, it should just reject it, and say user not found. It will then be queued up for sending on the sender's server.*

Jee

* this is assuming it's setup properly. Some email servers will just delete the email if they get a User Not Found error.

[Jeep Stone]

OK so if I went down the first option, I would just add the old server in as the secondary MX record on the new server (if I can)?

[Jeep Stone]

At the moment, the domain is stating 'The domain has been requested' on my control panel of the new host. It's been like this for over 24 hours now. Is it waiting for the old host to do something?