With your own domain you have your own unique email addresses. Without your own domain you would have to use your ISP account or a free email provider. Compare the email addresses below. Obviously the email addresses to your own domain is better. They build a stronger company identity and encourage trust.
People often use free email addresses to hide their true identity.
With your own domain people won't be wondering if that's what you're doing. Professionalism Your web address is part of your image. The public would certainly have a different image of them than they do today. The same goes for your business. You can enjoy the benefits of instant credibility and trust by having your own domain.