Email marketing is not only free (unless you used a paid service or purchase a contact list); it is a direct form of communication. You can easily personalise emails and create a tone of voice for your brand through an email campaign.
To create an effective marketing campaign using email distribution, it is important to gather email address and name of all potential or current customers and follow up on all leads. Lead generation can be time consuming but has a high rate of return compared to some advertising methods such as posters or flyers.
Think, when was the last time your hairdresser emailed you with a new promotion or a voucher because your birthday is coming up? How would this affect your loyalty to that hairdressers?