n8n Email Automation with Gmail: The AI Built It, I Fixed It

00:00 What this n8n email automation does

This is n8n email automation doing one useful thing. A client email comes in, n8n adds a row to my sheet, and a reply waits as a draft right under that email. The AI writes it for me. Nothing goes out until I press send. I'm building this with the n8n Assistant. I describe the workflow, it builds it, and I check what it got right and what I have to fix. I've actually used n8n many times before, so don't measure yourself against my times if you try this out for the first time.

00:31 n8n Cloud or self-hosted?

Maybe a quick note before you pick. I run my own n8n on a server, and for this video I used a fresh n8n Cloud trial. The n8n Cloud link is in the description. It's an affiliate link. If you subscribe, I earn a commission and you pay the same. n8n didn't pay for this video. So, for a first workflow, I'd start on cloud because Google sign-in and AI models work without any setup. It's a 14-day trial with no card, then from 20 euros a month on the annual plan. When the trial ends and you don't upgrade, n8n deletes the instance, so download your workflow, because you can also take it to a local instance, for example.

If you self-host, the software costs nothing, but you pay for the server and set up your own Google project, which can be a bit fiddly. Alright, we are in n8n, and this is the official website, n8n.io. We're gonna click Get Started now. Your instance is ready. Start automating. Okay, and that already gives me the n8n Assistant. This is actually what we want to try out. We can see here that we have 1,000 executions right now and 14 days left in the trial period, so you got 14 days to try everything out. And this is the Assistant here.

01:56 My prompt for the n8n AI Assistant

And I actually prepared a little prompt here, and this reads: Build a workflow called Client Email Drafts. Trigger: Gmail, when a new email arrives with the label Inquiries. I need the full email text, not just a snippet. Step one: Use an AI model with Gateway credits to read the email and return three fields: category, good fit, step two and so on. But I would just start this as is and see what actually happens. Let's go.

So we need to connect Gmail and Google Sheets because, well, that just makes sense. So we're gonna do this. Disclaimer: this is not my actual mail account. This is just a mail account that I use for testing, so I would advise, if you test stuff out, definitely don't use your actual mailbox, but use a test one instead. Same here, you should always go through the different things that are allowed. Both of them are connected to the n8n Cloud, which is super smooth. If you run this on your local server, this is way more fiddly to set everything up. So that's definitely a plus for the cloud version.

We also have this here prepared already, the Inquiries: Date, From, Subject, Category, Summary. And Gmail is connected, and we can already see the whole thing, and it's already testing. So this is super nice, to be honest, to actually see this being built out, because I remember even months ago, I think, but definitely years ago, you would need to build everything yourself, but it's super convenient that you now have this AI Assistant here in n8n. If you want this for your own inquiries and don't want to build it alone or need help with that, that's what my AI Workflow Sprint is for. Feel free to contact me.

The info is down in the description.

04:06 What the Assistant built

Okay, I built Client Email Drafts. It wasn't published yet, and I won't publish it without asking you. Very nice of you. Thank you so much. How it works: Trigger: Gmail checks every minute for emails with the label Inquiries and pulls in the full email text, not just a snippet. AI step: GPT-5.4 mini runs on Gateway credits, so you don't need an API key. Very convenient, thank you. A row goes into your Inquiries sheet with date, sender, subject, category and summary. This is good, because those are the five that we set up in here. Draft: It creates a Gmail draft in the same thread, addressed to the sender, with the subject Re: plus the original subject.

It only creates drafts and never sends anything. I like that. Two additions you didn't ask for. Duplicate check: Gmail sometimes returns the same email more than once. Interesting. To make sure each email is handled only once, I created a small data table called Processed Inquiry Emails. It stores the ID of each email after it's handled, and emails already in it are skipped. Though what I ask myself is, if I get another reply with the same subject, does it still skip this or does it work? Probably, because it's the IDs. It should work, but something I would need to test. Read status: emails are processed whether they are read or unread, and the workflow doesn't mark anything as read.

Testing so far: I ran it twice with sample emails. The routing worked both ways. The good fit email went to the draft step and the not relevant email skipped it, but those runs used made-up results for the trigger, the AI step, the sheet, the draft and the duplicate check, so nothing has run against your real Gmail or sheet yet. In the setup panel, pick your Inquiries spreadsheet and the tab to write to. Okay.

05:58 Mapping the Google Sheet columns

Let's make this a little bit bigger. Nice. So we can actually see the different steps here. New Inquiry Email, Skip Already Processed, this is the Classify and Draft, Log into Inquiries Sheet. Okay, we now need to actually choose a document here, because there's only the Inquiries document. But this is how a node looks. You get the schema, the table and the JSON. Here now: Map Each Column Manually. Map Automatically: Look for incoming data that matches the columns in Google Sheet. Let's do it manually.

From the Inquiry mail, we want to have the date here. It already switches to expression, which is good. Who's it from?

Value. I want to see the address like this. We want to have the subject, and category and summary come from the AI node, so we're gonna put the category here and the summary here, and that should do the trick. Let's hit the Execute Step. From, date, subject, category, summary. Yes, nice. Okay, now that actually works.

07:26 First test with a real email

The live test ran without errors, but it didn't test anything. The trigger found no email. Yeah, that makes a lot of sense. Put a test email in the Inquiries label. Yes, I prepared that. Those are coming from my personal mail. Okay, hit send. Let's see if it appears. Refresh. Boom. Okay, it's in here. It already has the Inquiries label.

Yeah, let's always allow. Okay, now we can see this live here as it actually works. And let's read the mail first: I run a small yoga studio in Austin and I spend about five hours a week answering the same questions about classes and memberships. Can you help me automate that? So this is a real inquiry. The live test worked. All seven steps ran on your real accounts with no errors and nothing simulated. We got it in here. The From is right. The time is also right. This is a good fit, and the summary is also correct. What we do have now is also a new draft: Hi Maya, yes, we can likely help with that.

Automating common questions about classes and memberships is exactly the kind of workflow we work on. Bam! That did actually work. And what we can do now is execute this again to see if the double check actually works. Same email as the previous, duplicate check. It set everything up as intended. I don't want to go into too much detail. If you have any problem with any of your n8n workflows, feel free to comment the questions below. Okay.

09:15 Teaching the AI how to reply

After all of this, I got $1.99 left, and I can always change this, though, to my own credentials, to my own API keys. And what we're gonna do is we're gonna scroll down all the way here, since there's no instructions here anywhere. We're gonna add the option, search for instruction. It's not actually in here. Did I miss the instruction? Oh, instruction, it's here. I missed it. Okay, so those are the instructions so far, because this is what the Assistant did, and I went a little bit more into detail. You can also check the video on how to let AI write more like yourself. There's some instructions in here on how they should reply, because, for example, we saw here in the drafts Best, Your Name.

Now it's gonna reply with Lukas every time. And I put in four more mails in the inbox, and

10:18 Four more emails: what went wrong

we're gonna let it run once again. Execute. Let's see if we get better draft results now and if everything else works as expected. Let's go through them. Client onboarding takes forever. This is a real one. At low prices. So this actually would be a good one to answer. This is not really a question. It's also weird that the other ones weren't put in here, because at least they should have gotten the Not relevant category. Let's run it again, see what happens. Skip Already Processed, so it stopped there. Let's see the Processed Inquiry Emails. Okay, there's only the two in here. Super weird. Let's do some troubleshooting.

11:13 Fixing it with the Assistant

Talking about bad prompts, this is definitely a bad prompt.

What problems did you notice? Okay, some emails got no draft. Wrong category. Let's submit this and see if the AI Assistant from n8n themselves can actually fix this. Speaking about drafts, but let's check this one here, which actually got created. Oh, it actually created the one for Daniel, but not this one.

Missing drafts weren't a bug. Those emails were never run through the workflow. When you click Execute, the workflow only fetches your newest email with the Inquiries label.

Because it came before the newest one? How can we make sure that all inquiries get checked? Okay, so that was the actual problem, because only that one counted as the newest one. It never added those three here, which makes a lot of sense, because it checks every minute, but if two emails come at the same time within that minute, one gets skipped. Yes, okay, switch. Let's check every five minutes. Yeah, that makes a lot more sense. But now that we schedule this to every five minutes, the label gets checked with every mail, and all the ones that are here in the Processed Inquiry Emails are being skipped, and all the new ones are being checked.

Quick correction here. I said that if two emails come at the same time, one gets skipped. That's only the test button, because it picks up the newest email. Once the workflow is actually published, which it wasn't here in the test, the Gmail trigger picks up every new one. So the problem came from the test and not from n8n itself. It was just because it wasn't a live trigger here. Okay, so the Assistant is ready.

13:20 Final run and publishing

A live run, clicking Execute would really do the following: Add three rows to your sheet, create two drafts for Rachel and Pierre. And once you're done with this, always make sure you actually publish, because until you publish, nothing is live, and the five-minute routine here wouldn't run.

Okay, so Website is being tagged as a Question. This is fine. Pierre wants help with his website, but the request is too vague to know what he needs. Not relevant, this is a sales pitch, and this is definitely a good fit. We should see drafts now if we refresh in Gmail, and those are actual drafts that could be sent out. So all the automation does is scan your mails and write in this Google Sheet here whether it's a good fit, a question or not relevant for you, and also, if it is either a question or a good fit, creating a draft in your mailbox that you can then go through and hit send or edit the draft or delete it if you think otherwise.

So I would say that was pretty good. The AI Assistant really worked well, and we created a new workflow that checks your mailbox for inquiries in less than half an hour, I would say.

14:56 Real client emails and the 5-minute catch

Don't point this at your whole inbox. Every email it processes is one AI call. One label is enough, and if your website form already sends you an email, that's your trigger. Before you run this on real client emails: that text goes through n8n to the AI provider. Check if that really fits your work. Here's the catch with the schedule the Assistant suggested. It runs every five minutes, whether there is an email or not. That's 288 runs a day. The starter plan includes 2,500 a month. So that's gone in about nine days. Test runs didn't count. My counter still says zero. So before you publish, set it to once an hour or go back to the Gmail trigger.

15:40 My verdict

My verdict: the Assistant got me most of the way, and very fast, but I still had to map the sheet columns, clean up the drafts and check every result. If you answer the same kind of inquiry every week, this is worth building. If you get two emails a month, it definitely isn't. So let me know what you think. Do you think this is helpful? Did you already set up automations like this? Let me know in the comments. My n8n guide and the AI Workflow Sprint are both linked below. And if this was useful, make sure to watch the next one. Thank you so much for watching, and see you again in the next video.