You can send emails to multiple recipients using Google's Gmail, but be aware of its stated limits and people's privacy expectations. Use a feature called blind carbon copy, or BCC, to protect your recipients' privacy, and use Google's contact group feature to manage lists of recipients. You might also want to use a spreadsheet mail merge tool to help you manage the list of recipients.
BCC for Privacy
The easiest way to send a mass email through Gmail is to simply add all your recipients' email addresses in the normal Compose interface, either by manually typing them in, copying and pasting them or selecting them from your Gmail contacts.
You can add them to the regular "To" line, but that will let everyone included on the email see, and potentially reply to, the full list of email addresses. To protect people's privacy, Gmail--along with essentially all other email services--provides a service called "blind carbon copy," or BCC, that ensures email recipients can't see each other's addresses.
To use it, simply click the Bcc button when you're writing an email in Gmail, and make sure to add the recipients' addresses to the Bcc line instead of the To line.
If you find yourself sending email to the same set of people again and again, you might want to organize them into a "contact group" that you can add to a Gmail email with one click.
To make a contact group, visit the Google Contacts page, click the Groups button, and then click New Group.
From that same page, you can click the Add Person button to add more contacts to the group, or click the Email Group button to send an email to the members of the group.
If the list of people you want to email is stored in a spreadsheet instead of in your Google Contacts, or if you need to do a little bit more personalization, such as including people's titles or editing other information in each email, you might want to use a mail merge tool instead.
There are a few tools available to do the job. Streak, a subscription service, offers a free plan along with higher-priced options with more features. A free tool called Yet Another Mail Merge lets you send emails you can personalize based on a Google Sheet spreadsheet, although you can only send to a maximum of 100 recipients per day, in accordance with Gmail's limits. For more advanced users, Google provides a tutorial on building your own custom mail merge tool using Google Sheets and Gmail.