The first question for people onboarding into the world of Google Workspace (welcome by the way!) is often "sooo, how can I send a quadrillion emails for free?". Spoiler: You can't. You'll thank us later.
Here is some background information why and some alternative ideas of what you can do - because nobody wants to send a quadrillion emails. There is always the overanxious event organizer or somebody who mistakes a change management campaign for "oh - just write an email". We feel your pain - this article is here to help you.
When talking about "Mail merge", I am summing up several features:
Sending massive amounts of emails (from dozens to tens of thousands)
Sending emails with differing content ("Dear Holger, good morning to you!")
Sending emails with tracking features, so you know when they have been opened
Hiding the sender of the email (don't confuse with send by group, which is perfectly legitimate)
Sending email with special features, such as AMP mail.
Note: Since this post came out, Gmail has introduced "multi-send mode" which does allow you to send personalized emails to up to 1,500 people/day. This is lower than your email limits and clearly meant as a "tool for the small guy/girl". It won't work a massive spam tool. I stand by this post!
Bam! like that. Look at the famous Limits article to see easy it is to get suspended.
Google aggressively defends its infrastructure against perceived spammers and will lock your account for extended periods of time if necessary.
... in more than one way: First, when your mass mailing is considered spam, that may harm your reputation in the market. You may have to apologize to your clients.
Second, sending enough spam messages may cause your company's legitimate emails going to people's spam folders. Not only clients talk. Their email systems talk, too.
A lot happens when you sent an email. It is scanned, retained, and a whole lot of other things to keep us safe. These systems are robust (because you are served by the best!) but any system can break. Spamming is considered endangering the infrastructure, which can have very serious consequences.
Also, you have many resources. But your clients may not, especially when they're not on Google yet. Your mass email may cripple your client's infrastructure - back to your reputation.
Unfortunately, most people who insist on using Gmail for Mail Merge want to do one-off mailings and are not really concerned with the impacts it has. They are mostly concerned with getting something quick and for free, and every communications team will join me in facepalming. As will every email networking engineer.
1. Efforts relying on email to get the word out have already failed.
2. Our email infrastructure is serious business and not for amateurs.
Probably not what people want to hear, but: Think before you mail. Unsolicited bulk email is near certain to go to trash.
Consider using Google Sites
Consider a campaign on Google Chat
Be patient. You will not be able to pull something together from one day to the next.
Emailing a group is usually okay - especially if the people you are emailing have opted into that group, or if the group is maintained by your territory's IT and you have their approval.
Emailing a group will, of course, not have any tracking or personalization capabilities. It's just a means of sending many emails. Be aware that there are limits for this, too.
Your internal communications team or your marketing team have (expensive) professional tools at their disposal. There are probably half a dozen marketing tools in the network that will reliably do what you want.
There is another possibility, which is to create a Sheets and arm it with Apps Script. You can find several templates if you look for them. They require some coding, in my experience too much for people without coding experience. This method actually sends emails from your account, as if it was you, so you are strictly limited in how many emails you send.
Thank you for reading!