Back to Blog
Strategy

What Is Email Marketing Automation? Sell Again to Existing Customers Without Growing Your Team

Sell again to existing customers without growing your team, with automated emails you set up once and use for the long term

July 20, 2026 5 min read

Email marketing automation means setting up emails to be sent to customers automatically based on predefined behaviours, such as a welcome email the moment someone signs up, or a reminder about an abandoned cart, without anyone having to press send each time.

Essential automations every business should have

The most cost-effective automations for SMEs are usually a welcome series for new customers and cart abandonment emails for people who almost bought but dropped off. Both are set up once and keep working on their own for the long term.

Tips to keep your emails from being ignored

Subject lines should be clear and to the point. Content should be short and concise, with a single clear call-to-action. Segment recipients by behaviour, such as existing versus new customers, to send content that matches their interests, which can significantly increase open rates. Also test different send days and times, because email-opening behaviour differs between customer groups and industries. What works for one business won't always work for another.

Don't forget to clean your email list

Email addresses that haven't opened anything for a long time should be separated from your main list, because they hurt deliverability and make everyone's emails more likely to land in spam. Cleaning your list periodically keeps your automations effective over the long term.

Want to start advertising without taking the risk yourself?

Starter package from just 6,900 THB 4,900/month, with a professional team to plan your budget

View packages