Can you guarantee better email deliverability?

Everyone wants better deliverability. When messages don't reach inboxes, you're missing out on an opportunity to connect with customers. So we're often asked:



Everyone wants better deliverability. It’s a worthy goal. When messages don’t reach inboxes, you’re missing out on an opportunity to connect with customers, plus you’re having to pay to send emails to people who will never see those emails. The thought of your messages bouncing or landing in spam…

So people often come to us on a mission to increase their deliverability. One of the most common questions we get is some version of: “Can you guarantee I’ll get better deliverability with you than I do with [Competing ESP]?”

First of all, we're really glad you take your deliverability seriously. We take it seriously too, which is why we’re constantly making sure that Mailgun’s infrastructure can help you reach a 99% (or even 100%) inbox rate. And it’s why we talk about email validations and dedicated IPs and other deliverability strategies.

But the idea of guaranteeing deliverability, that’s where we draw the line. There are a number of factors affecting your delivery rate, and many of them are outside of an ESP’s control. When we see ESPs advertising big deliverability claims and guarantees of 100% inbox placement rates, we get kind of mad because they’re not being real with you.

Let’s break down this question to what you really want to know – how you can achieve better email deliverability.

Learn about our Deliverability Services

Deliverability Services

Looking to send a high volume of emails? Our email experts can supercharge your email performance. See how we've helped companies like Lyft, Shopify, Github increase their email delivery rates to an average of 97%.

Can I get 100% deliverability?

Theoretically, yes. You can achieve a perfect delivery rate when:

You send engaging emails that don’t look like spam.

You don’t go into gimmicky, marketing speak or yell at your users in all caps or get exclamation mark happy!!!! Instead, you use my name (Hi, Nick) to make it personal, and you give me a valid email address to reply to. Spam filters have gotten pretty sensitive, so making your email content less spam-y requires consistent effort. This CAN-SPAM compliance guide gives you more tips for staying out of spam filters.

One thing to note: you can have 100% delivery with emails still landing in spam folders. The email was delivered. It was just delivered to the folder where emails go to die. But I consider the term “deliverability” to mean inboxing. Beware of anyone advertising 100% delivery and making no mention of deliverability.

You send these emails to actual people.

You validate email addresses on your web forms so you know the inboxes on your list really exist. (We can help you with this.) Once you’ve sent some emails, don’t forget to keep an eye on bounce notifications. If you clean out hard bounces and other dropped emails, your deliverability rate will increase. Pretty elementary, but if that perfect deliverability score is what you’re after, this can make a big difference in boosting your reputation. To help our users with this, Mailgun automatically suppresses email sends when they’ve previously bounced, complained, or unsubscribed.

These actual people actually want to get emails from you.

You collected email addresses through a double opt-in process so you can be certain the person that signed up is who they say they are. And even though they gave you permission initially, you let them opt out whenever they want through an unsubscribe link. One important thing to remember if you decide to change ESPs is to take your unsubscribes and other suppressions with you. That way you won’t start sending to mailboxes that have previously rejected you.

You pay close attention to the people on your list.

You know what your subscribers’ engagement looks like. This is where email analytics can really help. It’s no secret that ISPs pay very close attention to user engagement. If you continue to send to people who haven’t engaged with your messages in quite some time, it will undoubtedly hurt your deliverability.

At Mailgun, we recommend incorporating a “sunset policy” for your recipients. This means that if someone hasn’t opened your messages after a period of time (which varies depending on how often you send), you either a) remove them from your lists, b) send less frequently to them, or c) run a re-engagement campaign. If you get nothing from them on the re-engagement campaign, it’s time to remove that address.

You use an ESP that knows what it’s doing.

Your chosen delivery service actively monitors its environment, adheres to best practices, and gets rid of nefarious users. They warm up their shared IPs and guide users with dedicated IPs through that process. They require their users to use their own sending domain, strengthening the reputation of good senders and isolating them from potential spammers. It also helps when they can give you insight into your delivery failures so you can make some changes before your next send.

Ideally, your ESP has seasoned experts on staff who know deliverability in and out. These people have seen both failures and successes from senders, so they can give you advice on what works and what doesn’t. It makes a huge difference when you have an expert to rely on, set you up for success, and provide guidance on common pitfalls to avoid.


100% deliverability is like driving the speed limit 100% of the time. It sounds easy, but in the real world, it ain’t gonna happen. At the end of the day, getting better deliverability is the sender’s responsibility.

No deliverability guru or ESP in the world has a magic light switch they can flip to ensure 100% deliverability. The good news is that the strategies mentioned above are the same ones you can use to reach more inboxes. By keeping up with great email practices, you’ll be on the path to success.

If you’re already a big sender and looking for some extra guidance on best practices, talk to us about our Deliverability service, which comes with a dedicated technical account manager (like me) who keeps an eye on your email reputation and deliverability.

TL;DR: Can you get 100% deliverability? Sure. Will you get 100% deliverability? Highly unlikely. Is that okay? Yes. If you want to improve your deliverability, you can get pretty awesome results by sending engaging emails to actual people who agreed to receive them.

Learn about our Deliverability Services

Deliverability Services

Looking to send a high volume of emails? Our email experts can supercharge your email performance. See how we've helped companies like Lyft, Shopify, Github increase their email delivery rates to an average of 97%.

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