Home » HubSpot Digital Marketing Course » Fill in the blank: The ideal length of an email subject line is _____ characters. Fill in the blank: The ideal length of an email subject line is _____ characters. Advertisement 5shares Facebook LinkedIn Pinterest Twitter Email 41–50 55–75 10–20 75–100 Join our listSubscribe to our mailing list and get interesting stuff and updates to your email inbox. Thank you for subscribing.Something went wrong.We respect your privacy and take protecting it seriously