A personalized email address is a means of recognition. If professionals possess an email address on a custom domain tailored to their profession rather than Gmail or Yahoo, they will not only have a good first impression but also a reflection of what they do.
When you correspond with a customer or prospect by email, they’ll know that you take your business serious since you are not on a free gmail or yahoo email . The same is true if someone forwards one of your emails.
You can also separate your incoming email by its purpose. Having addresses like John@ThisName.com, Shopping@ThisName.com, Bills@ThisName.com and Spam@ThisName.com can help you compartmentalize your incoming emails.
A custom email address is also recovered a lot easier then a free one if you get hacked. You own the domain so you can change your password much easier than trying to contact tech support on a free email service.
Lastly, unlike your @att.net or @comcast.net internet provider-based email address, if you change internet providers, this address does not go away like theirs do.