Research suggests that subject lines of fewer than 50 characters result in higher open rates. This may be because many email recipients see chopped-off subject lines when they contain too many characters.
Furthermore, many users receive email messages on mobile devices, which can limit email subject lines to as few as 30 characters.
Try to keep your subject lines short and relevant, and put any unique or necessary information right up front - this can impact how many users actually open and read your email.
To help prevent your messages from getting lost in a cluttered inbox, eNotify displays the number of characters in your subject line, just below the subject line entry field on the Compose eNotice screen.