You can find software or apps online that validate email addresses in bulk or individually. There is usually a user fee associated with using these services. On Google, you can find listings of such services. Below, I have included links to two examples of email verification services.
An online website:
This website can validate individual email addresses and email addresses in bulk. To use the bulk email verification, a file containing the email addresses must be uploaded to the web page. Uploaded files to the web page are not saved for any reason.
Email Verification Software:
A number of downloadable email verification software names are listed. For privacy reasons, these listed software could be better than online email verifiers.
How can you do email verification for email marketing?