Don't have support registrations in the name of a specific sysadmin
Every so often at work you will buy something, sign up for a service, arrange a support contract, register for monitoring, or whatever with an outside company or organization. Not infrequently these things will ask you for an email address that will be both your organization's key to the service and the person who gets notifications about it (sometimes you have to pick a username or login too). Here is something that we have learned the awkward way: when you do this, don't just use your email address (and name, and so on). Instead, either use an existing generic group email address or make up a new service specific email address (often these will just be mail aliases that distribute the email to all of the relevant parties). There are two reasons for this.
The first reason is that it keeps a single person from being the critical path for things to do with the service. If things like password resets or approvals for some action go only to me because I used my own email address and you need to do one of these things when I'm sick or on vacation or very busy or whatever, well, we have a problem. Or at least an annoyance. Using a generic address that multiple people see avoids that problem; I don't need to wait for the single magic person to be able to deal with whatever they need to do.
The second reason is that, well, to put it bluntly: people leave eventually. If person X leaves and there are things tied to their email address, using their customary personal login, and so on, life is at least a bit awkward. You can make it work, but take it from personal experience, it still feels weird and not entirely right to log in somewhere as ex-co-worker X because that's just how it was set up.
(I imagine you can have lots of fun if there have been several generations of turnover. 'Why do we have to log in to this site as 'jane'? Who's Jane? Oh, she was here ten years ago.')
Consistently registering everything with a generic email address, a suitable generic login or username, and so on avoids all of that. When someone leaves nothing needs to change and there's no uncomfortable feel or awkward 'who is jane?' explanations in a few years.
(There are exceptions to this, of course. Sometimes a service has been built with these issues in mind, so it has groups and supports multiple accounts that you manage and so on. Sometimes a registration is genuinely personal and will only ever be used by you and it's okay for it to go away if you leave. Sometimes it's just in the nature of the service that everyone needs an individual login in order for things to really work. And so on.)
PS: The flipside of this is that if you're a service provider who has people register accounts with you, this is yet another reason that you really want to support changing logins.