Theory: Casual emails have been canibalized by Facebook and messaging products, leaving just the presumably more long winded emails that are more serious in tone.

If the lengthening indicates that vague subject lines such as "Hello!" or "Changes" is being replaced by something more specific like "Meeting at 3 p.m. agenda changed", then it's a good thing. I also like all the info in the subject line, such as "Free pizza in the break room <eom>"

Hypothesis: texting and Twitter have gradually forced (some) people to learn the skill of writing concise summaries of their thoughts, where centuries of schooling have failed.

I'm willing to buy into that. I'm very happy that they are doing that. But sadly, many are now tying to be more concise and the subjects now look like tweets with truncated words (please = pls) so its a new mind bender to decipher the subject. Lots of times its read the subject, go ??!?! and the read the body and spend a few mins trying to figure how the got the subject lines

When I start getting emojis in subject lines it will signal the death of email. ;-)

I answer tickets at my job and the subject line allows them to on forever, but due to our system the message will be truncated when it comes to me.

I have this one rep who will always send me tickets with the subject line reading, "Hi Randy Can you come take a look at this my software crashed three times and I don't know what to do I've tried restarting it and that hasn't seemed to help and then I got a bugsplat error message....."

I've explained to her 4x that the subject is truncated so all I see is, "Hi Randy Can you"

She still doesn't get it. Now I just walk over to her desk and ask what's up if she sends me something.

It's like trying to tech support my grandma, except this coworker is a 28 year old Berkeley graduate.

You can't just WONTFIX her with a "no info provided; cannot reproduce"?

Heh :) I think I might try that tomorrow!

I hope that people are slowly learning to create better titles. I fear that it's the increasing depth of "Re:"

or "Fwd: Fwd: Fwd: Fw: THE DONALD'S FIRST DAY IN OFFICE- OMG THE PERFECT DAY! "

^^ actual title of email my mother sent me yesterday :-/

I usually keep my subject lines slightly longer than usual to make finding them easier.

I like to include enough information in the subject line so that the recipient can make a reasonable judgement as to what the email is about and how much time they will need to read and answer the email. That gets harder with people you (e.g.) work with closely as the depth of the issues increases.

Screens are getting bigger, and more title can be visible.

If anything, screens are smaller than they were in 1999, when all mail was read on desktop computers.

Setting my massive monitor to the side (even though it's where I view by far the most email), my phone is 750 x 1334. My 1999 monitor was 1024 x 768.

The physical dimensions of the phone are smaller, but I hold it closer to my eyes than a monitor, so it's more about the resolution.

Looking at my inbox I would suspect the major culprit to be marketing mail. By far the longest subject lines come from marketing messages, most of which are using the subject line to make their plea or call to action. Emails from real people appear to have short subject lines. From my own experience, too, I tend to avoid wordy subject lines, saving detail for the message body.

The listserve option seems about the least likely to me simply because listserves have existed for a very long time. Unless mailing list names became much longer I would suspect that any changes in subject length would simply be in following larger trends (for example, the larger screens option).

The general trend upwards is interesting, but is anyone else more intrigued by the dip in 2008 followed by the spike in 2010?

My hypothesis is that this is being heavily influenced by automated emails from certain websites that the author is using over time.

And this could explain the general trend; that proportionally hand-written emails make up a smaller portion of our messages these days -- a quick glance at my inbox and automated 'notifications' are generally more likely to have longer subject lines.

(Original author here). I suspect the 2008 strangeness may be an artifact of my corpus: I have two email collections, both for the same address, but with different spam-filtering etc. I'd be interested to see if it is replicated in other email collections.

People are using the subject line to contain the whole message?

I was wondering the same. Email bodies are to blog posts as subjects are to tweets?

It would be interesting to look at the data for how many 1, 2, and 3 word subject lines there are over time. Maybe fewer "Hello" or "Thank you" subject lines as more people got used to the idea that it's good to be specific and informative in the email subject.

Can confirm firsthand. Started a new job less than a year ago. My new boss shuns/avoids/fears IM, so he'll send me emails with the message contained in the subject line. Strikes me as a little backwards, but he's 50 years old and prefers it to IM...

I find it easier - at least it's all centralised and searchable. No 'did they send an email, or an IM?'

English is quite terse. Perhaps the development of non english languages.

This was an almost all-English collection of emails. I'd be very interested to see if the trend is similar in other languages. If you're interested, the accompanying code for the blog post should be able to parse mbox, Maildir and notmuch databases of emails. https://github.com/dannyob/lengthysubject