The previous version of my website ran on WordPress. I used a hosting company that would automatically update the code for me when WordPress released an update.
Unfortunately, the host's upgrade email fell way short of the mark:
Subject: Upgrade to WordPress 6.1.1 Complete
"Ah great, all handled by the hosting company"
We attempted to automatically update your WordPress sites to version 6.1.1, but our tests did not pass on some or all of your installs.
"Did not pass?"
Most people would read "Upgrade Complete" as it was successful completed and archive the email. Not that an upgrade was started, failed, and still needs to be done.
Misleading customers and prospects with bad subject lines is easily avoided with a little thought. My writing template includes this prompt to me right at the top:
Restate the promise made by the title
The email's subject line is a promise that the body needs to fulfill. If it doesn't, you either need a new subject line or a new body.
You can still be cute, clever, and crafty in your subject lines (or any other adjective). Just make sure it's really clear to the customer once they get into the email content.
That said, if you're working on customer retention (perhaps with Repeat Customer Insights' analysis), tuning your email subject lines can be wonderful to improve your email performance.
Clear email subjects get the email opened. Email opens get the clicks. Clicks get customers buying.