I know the idea seems simple but people are actually really bad at email subject lines. I used to teach this informally to my customers—mostly an over-65 population of rural folks. Mostly slightly wealthy retirees; mostly educated. They really struggled.
Some of this is a UI problem: what you call something and how you frame it really matters. Subject lines are big, blank, and up front. They are an open ended text field, prompting in a different context than displayed.
Subject lines are also _above_ the body, and people tend to execute user interfaces to to bottom, especially when they're form-like.
This means that people either need to try to describe an email they have not written yet, or need to loop back. Or not try. Mostly: they don't try. The cognitive load is too high, and they struggle to know what "the right way" is. They cannot empathize enough with a hypothetical receiver to guess the context it will be received in accurately, and they bail out.
I used to teach the military style BLUF: bottom line up front. I'd say "write your email. Okay, now what's the most important part, probably near the end. Conclusion, or action you want them to take. There's your subject line. Also it's okay to make it the first line too."
If they're really clever, I'd teach them what TL;DR means.
@aredridel Did they also have such problems with "purely transactional" emails (asking a company/institution to sell them something/do something/...)?
I'm surprised that older people have this problem: I would expect that they had much more exposure to business mail in their life, which has a very similar concept (at least the DIN norm for letters does treat it as a very obvious part of letter, on a similar level of obviousness as your/mine reference number). Thus I wonder if that's purely a problem in personal emails, where there is not necessarily a single thing they're trying to achieve via the message, or if my assumptions are wrong.
@robryk A couple of exceptional customers though: they had very rigidly formal ideas of business comms, so anything more trivial than a single request required a document _as an attachment_.
"Here is my request, please attend to it." (attached letter, in business standard format, as a word document)
"Here is my order", attached PDF, with the order written out as an order form.
@robryk They mostly don't send those emails, only receive!
But even sending those they struggle. Though I think I can characterize some of how: they can't imagine the context of the receiver. They'll treat them like an unhelpful store clerk — very Karen energy — because since they're struggling with the technology, they're already on the defense and going to take it out on others.
They do not know how to insert themselves into someone else's workflow, and can't even imagine it.