Sending the same email to multiple recipients at once is known as bulk email. You might also encounter similar terms, such as mass email or email blast. They are virtually the same thing.
Sending bulk emails is tricky without proper tools. Marketers are aiming to get the best results they can, and premade and mobile-friendly email templates come in quite handy to optimize the emails for different inboxes.
With that said, it is important to note that bulk emails eliminate personalization. One of the downsides of such an outreach form is that your messages become too generic, resulting in fewer positive responses.