Guessing whether people will unsubscribe from your mailing lists
Suppose that you have an administrative mailing list (or mailing lists), you understand that people can always unsubscribe one way or another, and you want to have some idea if people are going to do so. Here is my modest suggestion on a simple question to ask yourself about the messages going to the mailing list: are the mailing list messages actionable?
(Alternately you've been forced to run some mailing lists that people can't officially unsubscribe from and you'd like some guess at how many people actually read the messages.)
'Actionable' is jargon, but it's useful jargon. An actionable message is one that causes people to do things. So, does your average message tell the average recipient about something that the recipient needs to do (or know) right now or very soon? If they do not, some recipients may find the messages interesting but I think that a lot of people won't and are going to drop them.
(But, you say, your messages are full of interesting things. That's nice, but look, would your 'interesting things' go even moderately viral on Facebook or Twitter or wherever, even among a limited audience? If the answer is 'of course not' then they are nowhere near as interesting as you think. Being genuinely interesting is a very, very high bar.)
Obviously, the more actionable to the more people the better off you are and the less actionable you are to fewer and fewer people, well, that's not good. Completely non-actionable cheerful messages from eg your Dean (or some other high manager of your choice) almost certainly go straight to the round file.
(The unfortunate but honest truth is that today we simply don't have a good communication system for these sort of newsletter type things, at least if they're supposed to be relatively private. Email has stopped being it for all sorts of reasons that I don't feel like trying to write down in this entry.)
Logins and related things really do change, and for good reasons
Every so often it's popular to say that you will never, ever change a (Unix) login, an assigned email address, or whatever. No direct renamings, no new account to replace the old account, no nothing. Generally this attitude comes with a certain mixture of 'you should have got it right the first time' and 'if your login is less than ideal it doesn't really matter'.
This is wrong (and arrogantly blind). People periodically have excellent, compelling reasons to change their login et al and you are eventually going to have to change them one way or another. If you aggressively stick to your 'no changes' view, it's quite possible that very bad things will happen; one of the least bad ones is that important people will quietly leave your organization.
Let us take the most straightforward and obvious example. Suppose a married woman has a login, and of course when it was created it followed your common pattern of having her last name in it. Oh, and when she married she took on her husband's last name, because this is still common. Then one day she gets divorced and of course changes her last name back to her own. This is an excellent, compelling reason to rename her account, or rather two reasons at once. First, this woman is going to be want to be called (in logins, email addresses, etc) by what is now her actual name. Second, she is quite possibly not going to want to be reminded of her ex-marriage and ex-husband every time she logs in, gets email, has to send email, and so on.
If you tell this woman 'sorry, we're still not renaming your login, that's our policy', what you are doing is giving her a great big middle finger. If she has actual power in your organization, your policy is probably not going to last long and you will have created a bunch of bad blood. If she does not, any number of things may happen, such as her quietly resigning so she can go somewhere where she is not frequently reminded of her ex-marriage and how insensitive your organization is.
This is far from the only case where there are excellent reasons to change a login. It's simply an obvious one with a not uncommon situation where hopefully everyone can see the real injury done by not changing the login. People really do have really good reasons to change their login, reasons that they could not possibly have predicted in advance and so avoided. They are not being irrational or picky or any number of other things. And sooner or later you will wind up changing someone's login.
(In a relatively small environment it's possible for this to only happen very infrequently and you might actually never have it happen while you work for a particular place. In a large environment it probably happens relatively frequently.)
The corollary of this is that as much as possible you should design your systems so that they at least accommodate login changes from the start. Don't assume that logins, email addresses, names, and so on are unchanging. If you need an unchanging primary identifier for people, make it a meaningless one (a GUID or a random number is good).