How to Send Marketing Emails That Actually Reach Your Clients' Inboxes

Petboost already handles your day-to-day appointment communications: booking confirmations, reminders, updates, report cards, and payment receipts all go out automatically without you lifting a finger. That's operational messaging, and it's taken care of.

But you might be wondering: does Petboost do email marketing too?

We don't. And if you're doing email marketing to clients (seasonal promotions, holiday reminders, referral campaigns, newsletters) you should think carefully about how you're doing it.

There's absolutely a place for marketing emails in a pet business. A well-timed message about booking early for the Christmas rush, a reminder that it's flea season, or a "we miss you" nudge to lapsed clients can all drive real revenue.

But here's the problem: with recent changes to Gmail, Outlook, and most major email providers, it's harder than ever not to end up in spam. Google started actively rejecting non-compliant emails in late 2025. Microsoft followed suit. Yahoo tightened its rules. The inbox is a harder place to get into than it's ever been.

If you're using Mailchimp, Constant Contact, or any email marketing tool and just hitting "send" without understanding what's changed, a significant chunk of your messages aren't being seen. Industry data suggests roughly 14% of commercial emails globally never reach the inbox. For small businesses sending through shared marketing platforms without proper setup, that number can be much worse.

Here's what's actually going on, why it matters for pet businesses specifically, and how to send marketing emails that actually work.

What Changed? Gmail and Microsoft Rewrote the Rules

In February 2024, Google announced sweeping new requirements for anyone sending bulk email to Gmail addresses. Microsoft followed in May 2025 with nearly identical rules for Outlook, Hotmail, and Live.com. Yahoo and Apple introduced similar standards around the same time.

The big shift: these aren't guidelines anymore. They're enforced.

Since November 2025, Gmail has been actively rejecting (not just filtering, rejecting) emails that don't meet their requirements. Microsoft is doing the same. Your email doesn't quietly land in spam. It bounces. It never arrives. And you'll never know unless you're checking.

The core requirements that all three major providers now enforce for bulk senders are: proper email authentication (SPF, DKIM, and DMARC protocols configured correctly), a one-click unsubscribe option in every marketing email, spam complaint rates kept below 0.3%, valid sender addresses that can receive replies, clean mailing lists with low bounce rates, and transparent subject lines that match the content.

Most pet business owners have never heard of SPF, DKIM, or DMARC. That's completely fine: you shouldn't need to. But someone involved in your email sending setup needs to have these configured, or your emails are going nowhere.

Why This Hits Pet Businesses Harder Than You'd Think

Large companies with marketing teams and dedicated IT support adapted to these changes quickly. They had the resources to audit their email infrastructure, configure authentication protocols, and monitor compliance dashboards.

Most pet businesses don't have a marketing team. You're a groomer, a daycare operator, a trainer, a dog walker, and you're also the bookkeeper, the receptionist, the social media manager, and apparently now the email compliance officer.

When you signed up for Mailchimp three years ago, you set up a template, imported your client list, and started sending. It worked. But the rules have fundamentally changed since then, and if you haven't updated your configuration, your emails are increasingly likely to be filtered, junked, or blocked entirely.

Here are the specific ways this plays out for pet businesses:

Your seasonal reminders aren't landing. That "Book early for Christmas boarding" email you sent to 200 clients? If your domain authentication isn't set up properly, Gmail might reject it before it ever reaches their inbox. You'll see "delivered" in your Mailchimp dashboard because the email was accepted by the server, but that doesn't mean it reached the inbox.

Your re-engagement campaigns are hurting you. Sending a "We miss you!" email to clients who haven't booked in six months feels like smart marketing. But if those addresses are outdated, inactive, or if those clients have been ignoring your previous emails, you're actually training spam filters to distrust all your future sends. Low engagement tells Gmail your emails aren't wanted.

Your shared sending reputation is dragging you down. When you send through Mailchimp, your emails go through shared servers alongside thousands of other businesses. If other senders on the same infrastructure are generating high bounce rates or spam complaints, the reputation of those servers drops, and your perfectly fine email gets caught in the crossfire.

The Two Types of Email Your Business Sends (And Why It Matters)

Before we go further, it's worth understanding the distinction between the two types of email a pet business sends, because they have very different deliverability profiles.

Transactional emails are triggered by an action. A client books an appointment, they get a confirmation. Their appointment is tomorrow, they get a reminder. Their groom is complete, they get a report card. These are expected, timely, one-to-one messages that recipients want to receive. They have high open rates, low spam complaints, and inbox providers treat them favourably. This is what Petboost handles for you.

Marketing emails are sent by you, on your schedule, to a list of recipients. They're promotional in nature: holiday offers, seasonal tips, referral incentives, business updates. Even when the content is useful and relevant, inbox providers treat them with more scrutiny. They're more likely to be filtered into the Promotions tab, flagged by spam filters, or (under the new rules) rejected outright if authentication isn't correct.

The challenge is that most email marketing tools handle both types of email through the same infrastructure, and in doing so, they apply marketing-style formatting and sending patterns to everything. That's the wrong approach.

Your operational messages should be handled by your booking system (where they're accurate, timely, and sent from trusted infrastructure). Your marketing emails need a different strategy, one that accounts for the new reality of inbox deliverability.

How to Actually Send Marketing Emails That Work

If you're going to do email marketing (and you should, when done right) here's how to make sure your messages actually reach your clients.

1. Get Your Authentication Right

This is the unsexy but non-negotiable foundation. If your email domain doesn't have SPF, DKIM, and DMARC properly configured, nothing else matters. Your emails will be rejected.

SPF (Sender Policy Framework) tells receiving servers which mail servers are authorised to send email on behalf of your domain. Think of it as an approved sender list.

DKIM (DomainKeys Identified Mail) is a digital signature that proves your email wasn't tampered with between sending and delivery.

DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together and tells inbox providers what to do if authentication fails: quarantine the email, reject it, or let it through.

If you're using a custom domain for your business email (e.g., jess@pawsandclaws.com.au rather than a Gmail address), you need these records configured in your DNS settings. Your domain registrar or IT support can do this, and most email marketing platforms provide instructions.

If you're sending marketing emails from a generic Gmail or Outlook address, you're riding on Google's or Microsoft's own authentication, which works, but limits your control and branding.

The key thing to understand: these aren't optional anymore. Google, Microsoft, and Yahoo all now reject bulk email that fails authentication. Even if you're sending fewer than 5,000 emails a day (which most pet businesses are), proper authentication still significantly improves your inbox placement.

2. Send Plain Text, Not HTML Templates

This is the insight that most pet business owners miss, and it's the single biggest change you can make to improve your email deliverability.

The fancy HTML templates in Mailchimp (branded headers, images of happy dogs, coloured buttons, styled footers) look professional. But they also look like marketing. And inbox providers are designed to filter marketing.

Plain text emails, or lightly formatted emails that look like they were typed by a real person, consistently outperform HTML templates in deliverability and engagement. This is well-documented across every service industry. Companies sending hundreds of thousands of emails have found that stripping out the HTML, removing the images, and writing like a human is the most effective way to land in the inbox.

Here's why:

Spam filters trust plain text. Minimal code, no tracking pixels, no image-to-text ratio concerns, no embedded links triggering pattern-matching. Plain text emails look like personal correspondence, and spam filters are optimised to let personal emails through.

Your clients actually read it. Which email are you more likely to engage with?

Option A: A branded HTML template with a header image, a "BOOK NOW" button, and a footer full of social media links.

Option B:

Hi Sarah,

Quick heads up: we're fully booked for the week before Christmas, so if you'd like to get Bella in for a holiday groom, now's the time. You can book through your Petboost account or just reply to this email and we'll sort it out.

Cheers, Jess, Paws & Claws Grooming

Option B lands in the inbox. Option B gets read. Option B might even get a reply, which signals to Gmail that future emails from you are wanted.

It works on every device. HTML emails break. Formatting that looks perfect in Gmail on desktop renders differently on the Outlook mobile app. Images get blocked by default on some clients. Buttons don't render. Columns collapse. Plain text just works, everywhere, every time.

3. Write Like a Human, Not a Marketing Machine

Modern spam filters are powered by AI and trained on patterns. They don't just scan for dodgy keywords like "ACT NOW" or "FREE OFFER." They analyse the overall structure and predictability of your email. If it looks like every other marketing blast (same format, same structure, same type of language) it gets filtered accordingly.

Here's what to avoid: all-caps subject lines, excessive punctuation, generic marketing phrases like "Don't miss out!" or "Limited time offer!", multiple hyperlinks or tracking URLs, and image-heavy layouts with minimal text.

Here's what works: short subject lines (under five words), conversational tone, specific details (pet names, service types, dates), a clear reason for emailing, and an easy way to respond or take action.

Your clients chose your business because of the personal touch. Your emails should reflect that.

4. Keep Your List Clean

Every email you send to an invalid or outdated address increases your bounce rate. High bounce rates damage your sender reputation. A damaged sender reputation means future emails, even to perfectly valid addresses, are more likely to land in spam.

Remove hard bounces immediately. If an email address doesn't exist, take it off your list. Don't keep sending.

Remove soft bounces after three attempts. Temporary issues like full inboxes resolve themselves. If they don't after three sends, the address is probably abandoned.

Re-engage or remove inactive contacts. If a client hasn't opened any of your emails in 60+ days, they're either not seeing them (deliverability issue) or not interested. Either way, continuing to send to them is hurting your metrics. Send one re-engagement email ("Still want to hear from us?") and if there's no response, remove them from your marketing list.

Never purchase email lists. This cannot be stressed enough. Purchased lists contain outdated, invalid, and often fabricated addresses. They'll spike your bounce rate, trigger spam traps, and potentially breach Australian privacy law. It's the fastest way to destroy your sender reputation.

5. Include a One-Click Unsubscribe

This isn't just best practice: it's now required by Gmail, Yahoo, and Microsoft for any marketing email. Every marketing message you send must include a clear, easy-to-find unsubscribe option.

This might feel counterintuitive. Why make it easy for people to leave your list?

Because the alternative is worse. If a recipient can't easily unsubscribe, they'll mark your email as spam instead. Spam complaints are the single most damaging signal for your sender reputation. Gmail requires you to keep your spam complaint rate below 0.3%, that's 3 complaints per 1,000 emails. One frustrated client hitting "Report Spam" because they couldn't find an unsubscribe link does real, measurable damage.

A visible unsubscribe link actually protects your deliverability. The people who unsubscribe weren't going to book anyway. The people who stay are engaged, and that's the audience you want.

6. Be Strategic About Volume and Frequency

Inbox providers monitor sending patterns. Sudden spikes in volume (say, you normally send 20 emails a month and suddenly blast 300 for a holiday promotion) trigger suspicion. Consistent, predictable sending patterns build trust.

For most pet businesses, a monthly or bi-monthly marketing email is more than enough. Your clients don't need weekly newsletters. They need timely, relevant messages that respect their inbox.

If you're sending marketing emails for the first time from a domain or address that hasn't been used for bulk sending before, start small. Send to your most engaged clients first: the ones who book regularly, who open your emails, who reply. Build engagement history before expanding to your full list.

Should You Even Use Mailchimp?

This isn't a blanket "don't use Mailchimp" message. Mailchimp, Constant Contact, and similar platforms are legitimate tools that serve a purpose. If you're sending regular marketing campaigns to a large list and you understand the deliverability landscape, they can work.

But for most pet businesses, the answer to "should I use Mailchimp?" is: probably not, and here's why.

You're paying for features you don't need. Most pet businesses send a handful of marketing emails per month. You don't need A/B testing, audience segmentation by purchase behaviour, drag-and-drop builders, or advanced automation workflows. Mailchimp's free tier is limited, and the moment you want basic features, you're paying $30-$80+ per month.

The HTML templates work against you. Mailchimp's whole value proposition is making emails look "professional" with branded templates. But as we've covered, those templates are exactly what triggers promotional filtering and spam detection. You're paying for a tool that makes your emails less likely to be seen.

Shared infrastructure carries risk. Your emails go through the same servers as thousands of other senders. Their behaviour affects your deliverability. You have no control over this.

You need to manage authentication yourself. Mailchimp requires you to configure SPF, DKIM, and DMARC records for your domain. If you didn't do this when you signed up (and most small business owners didn't) your emails have been flying without proper authentication this entire time.

The alternative for most pet businesses is simpler than you think: send marketing emails directly from your business email account. Write them as plain text. Send them to a clean, engaged list. Keep them personal, relevant, and infrequent. You'll get better deliverability, higher open rates, and you won't pay a cent for an email marketing platform.

For larger operations that genuinely need a marketing platform, look for tools that prioritise deliverability over design: tools that make plain text easy, that handle authentication for you, and that provide clear deliverability reporting.

A Quick Checklist Before You Hit Send

Whether you're using Mailchimp, another platform, or just your regular email, run through this before every marketing send:

Authentication. Is your domain configured with SPF, DKIM, and DMARC? If you don't know, ask whoever manages your domain or use a free checker tool online.

List quality. When was the last time you cleaned your list? Remove anyone who's bounced, unsubscribed, or hasn't engaged in 60+ days.

Format. Is your email plain text or lightly formatted? Strip out heavy HTML, images, and branded templates. Write like you're emailing a client, not designing a brochure.

Content. Does your subject line look like a real email or a marketing blast? Is the body conversational and specific? Does it include the recipient's name or their pet's name where possible?

Unsubscribe. Is there a clear, one-click unsubscribe option? It's not optional anymore.

Volume. Are you sending to an appropriately sized, engaged list? Avoid sudden spikes in volume.

Reply address. Can recipients reply to your email? A no-reply address signals to inbox providers that you don't want engagement, which hurts your reputation.

The Bigger Picture: Communication Is Part of Your Service

The pet businesses that retain clients the longest aren't always the cheapest or the fanciest. They're the ones that communicate well.

For the day-to-day (confirmations, reminders, updates, report cards, payment receipts) let your booking system handle it. That's what Petboost does, and it does it in a way that's accurate, timely, and deliverable by design.

For marketing (the seasonal nudges, the loyalty touchpoints, the campaigns that bring lapsed clients back) do it thoughtfully. Keep it personal. Keep it plain. Keep it honest. And make sure it actually reaches the inbox.

Your clients trust you with their pets. The least you can do is make sure your emails are worthy of that trust.

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