A short subject line is fully readable in most email clients and is also quicker and easier to understand for most recipients.
Furthermore, short subject lines in your emails raise the open and click-through rate. Emails with subject lines with ‘0 to 49’ characters have an opening rate that’s 12.5% higher than that of subjects with ’50 or more’ characters.
The click-through rate for subject lines of ‘0 to 49’ characters is 75% higher than the CTR of emails with subject lines in the ’50 or more character’ range.