Domain-based email addresses such as sales@yourdomain.com look professional, and show you're serious about your website design business. While SiteSwan does not offer email hosting, there are many options available to you at a relatively low cost ($5-$10 per email address). Here are a few options to consider...
Your domain registrar
Contact the company you bought your domain name from because almost all of them offer the option to add custom domain-based email addresses to your account.
Google Workspace (formerly G-Suite) is a popular provider of domain-based email addresses. Plus, you'll have access to Google's suite of tools which includes Gmail, YouTube, Drive and more.
Microsoft
Microsoft 365 (formerly Office 365) is another solid option that includes access to apps like Outlook, Word, and Excel.