This email seems to have been sent to people who use an email address associated with a domain name that they own. Although this email claims to have come directly from your domain, this is the email address it was actually sent from: <firstname.lastname@example.org>
Your online email provider probably doesn’t care which device you use to access your email, and if they do, they WILL NOT ask you to validate your email address.
I don’t know where you would be taken if the “Validate” link was working, but my guess is that you would be asked to enter your email password so the scammer could take over your email box and email a dodgy link to all your contacts.
If you do use email associated with your domain name, you will probably know that there is no such person/thing as your “Mail Service Administrator”. You own the domain name and pay for the hosting (or the email service) and YOU are the administrator.
If you think you have accidentally clicked on the link and given your password to the scammers, login to your domain hosting and change your email password.
We noticed an attempt to sign into your mailbox email@example.com from an unknown Device.
For security reasons, your account has been restricted. Click on VALIDATE to keep your firstname.lastname@example.org up
Noted: Access to email@example.com will be restricted within 8 Oct 2020
Your security is our primary concern.
yourdomain.com Mail Service Administrator