Be Careful Sending Emails on Mondays

Posted By on Dec 19, 2016 | 0 comments


Your Monday morning alarm might be the worst sound in the world. Weekends fly by, but Mondays drag on forever. As avid Office Space fans, we wondered if having a “case of the Mondays” was an observable phenomenon. Our finding? Monday really is the worst day of the week: it’s when people make the most mistakes in their email subjects (which, as we will show, matters), as well as the day with the most negative email subjects.

Subject lines from over 250,000 emails were passed through an automated grammar-checking library (similar to the one in Microsoft Word) to measure error rates and sentiment over the course of the week. We first looked at the number of subject line errors flagged over the course of a week, and sure enough, Monday was when subject lines were most error-prone.

And such errors have consequences! The more errors an email’s subject had, the less likely it was to get a response. Emails without any subject line errors received a reply 34% of the time, while those with an error had response rates of 29%.

Subject Errors Response Rate
No Error Detected 34%
Error(s) Detected 29%

Response rates thus fell 14% when subjects had one or more mistakes (relative to response rates for emails with error-free subjects.)

This isn’t the first time we’ve seen a trend between subject lines and response rates: emails with extremely short or long subjects also have lower response rates. But subject errors also correlated with lower response rates when we looked only at emails with four-word subjects. So while subject length and subject errors can both affect response rates negatively, it appears they act independently of each other.

Subject Errors vs. Response Rate, Four Word Subjects
Mistake Count Response Rate
0 41%
1 38%
2 34%
3 34%
4 34%
5 30%

And not every subject line error had the same effect. The most significant error was starting a subject sentence with a lowercase letter. Such emails only got a reply 28.4% of the time, compared to a 32.6% response rate for those with proper subject capitalization. You could be one (shift) keystroke awake from boosting your response rates by 15%!

But wait, there’s more (proof Mondays are terrible)

Your propensity to make mistakes isn’t the only thing worse on Mondays, so is your mood. We looked at average subject line sentiment (a measure of positivity), and found that emails sent on Monday are the least positive. Not only do emails sent on Mondays have the lowest subject sentiment on average, it’s a steep drop off from Sunday, which has the most positive email subjects.

“Wish it was Sunday, ’cause that’s my fun day”

Alas, Boomerang can’t make Mondays disappear, but we can help you make them more manageable. You can write Monday emails ahead of time and schedule them to send later so you have time to review them before they go out, snooze emails that you just don’t want to deal with right now (but need to remember to respond to later on), or set up a recurring email to eliminate an email you’d otherwise have to type out each Monday. Or, use the new-and-improved Inbox Pause to avoid receiving any emails on Monday at all!

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