Local or remote DNS has nothing to do with what I'm bringing up.
If a server has active mail for that domain, it will not check DNS. It has always been that way and not only for Plesk.
I was merely bringing it to your intention.
An active mailserver without MX-records pointing to it can therefore be
considered a misconfiguration.
I've seen it happen with me and I've seen it happen with others, even with big Microsoft Office.
I would call it a misconfiguration...
It's somewhat debatable (
until they start complaining they never get any mails anymore from that nice man who also happens to be a client of yours).
I do agree however you should be able to keep your mails if the mailservice is disabled.
The new service could break down or some mails didn't migrate.
But Plesk never ever deleted mails if I disabled the mail service for that domain (I'm using Plesk for 20 years).
Or are you disabling the mailserver for the whole system? Why would you do that?
You are aware that Plesk is intended for providers and not for 1 domain?
Still, it doesn't mean you can't use it for 1 domain.
For years I've disabled the mail service for a specific domain and it never ever deleted any mails.
I therefore don't understand the problem, unless you disabled of removed the mail service.
In that case, that's asking for it.
When a customer migrates their domain to MS, they also need to migrate the content of their mailbox to MS. Customers often want to keep the mailboxes in Plesk for a while before they are finally deleted. But that only works if the email service is activated.
"But that only works if the email service is activated"
That's a strange offer to your customer and it will likely get you unnecessary questions.
You mean that they will continue to have your mailserver in their client even though it has become static?
I disable the mailserver (
mainly to prevent local delivery).
I tell them that I continue keep their mails on my server in case they are concerned and I will keep them for a while and if necessary inform them before I delete them.
I've even written a script that will tell me if there are domains with mail service enabled whilst MX is pointing elsewhere.