Deliverability & Self-Hosting Newsletters


Self-hosting isn’t for everyone. But this is also one of those situations where having the information can empower you to make decisions that will better serve you in the long run.

There is absolutely nothing magic about self-hosting. It’s basically what an Email Service Provider (ESP) like Mailchimp or Mailerlite is doing, and then they are “renting” out “Brand” space to you. In fact, there are some self-hosting apps that have a license available for multiple sites that allow you to do the same thing on a smaller scale. If you have a small group of authors you trust and work with regularly, purchasing a license for multiple sites might bring the costs down even further.

After reading this, if you decide to give self-hosting a go, there are step-by-step instructions for getting SES up and running (you have to jump through some hoops) at the end of this document. I’ve also included several “hacks” that might be stopping you from giving self-hosting a shot.

In the words of P!nk, Let’s get this party started!

IP Reputation

When you send out a campaign, even if you’ve authenticated your domain and verified your email, it’s still coming from an IP.

Right about now, you’re probably wondering what an IP is and what does it matter. IP stands for Internet Protocol and is like a phone number for the server your campaigns are sent from. And right about now you’re thinking you verified your domain and did that dkim thing, so you don’t have to worry about IPs.


The domain verification and dkim thing just tells everyone who’s checking that the campaign is coming from you and not someone pretending to be you. It’s like the blue check on Twitter.

When you sign up with an ESP or Amazon SES, you’re assigned an IP (or group of IPs) associated with a server and will likely only be moved to a new IP (or group) under the rarest of circumstances.

The very first thing a provider checks when an email knocks on its door, is the IP. Does the IP have a good reputation? Or does it have the reputation of a door-to-door salesman peddling everything that exists (and in some cases doesn’t exist) under the sun?

If the IP associated with your mailing list has a good reputation, that’s not a problem. The provider will open the door. If the IP doesn’t have a good reputation, they are slapping a do not enter sign on the door. Where the provider sends that email once they open the door (the inbox, promotions tab, or spam folder) is also determined by the IP’s reputation.

The reputation is based on several criteria. I’ve included the averages across all industries and the limits imposed by SES before they suspend your account so you have a benchmark.

Bounces (10% for probation 2-3% is normal)

There are two types of bounces. Hard and soft.

Hard bounces are where the provider rejects the email because the address it is sent to is either non-existent or invalid, or because the provider has blocked the IP (or IP group).

This is one reason why a double opt-in to confirm the email address or sending a large list through a cleaner is important. ESPs and SES do not like hard bounces. Hard bounces are marks against your list. And a huge mark against the IP’s reputation. The idea is that good senders care about things like a healthy list and healthy lists don’t have a lot of hard bounces, therefore, a lot of hard bounces means the list doesn’t belong to a good sender.

Soft bounces are caused by a full inbox, an email that’s too big, or a server that’s down. Typically, soft bounces aren’t held against your list, but they can if you get multiple soft bounces with the same email over several campaigns. (If you use an ESP, they usually stop sending a campaign to an email address after 2 or 3  soft bounces, but will not flag the email address as undeliverable. If you self-host, you can set up how many soft bounces you’re willing to accept per campaign.)

While you can’t control for soft bounces, you can and absolutely should control for hard bounces. Hard bounces can kill an IP’s reputation if you aren’t careful.

Opens (20%) and Clicks (2.6%)

Every time someone opens your email, it helps the reputation of the IP. It means you are sending content that someone wants to see. It’s even better if you can get a click because that shows engagement.

Opens and clicks are important to an IP’s reputation, but the more important metric for list owners is the click to open rate. It’s determined by taking the total number of unique clicks and dividing it by the number of opens. This rate tells you how engaging your email is. (14.3%). I haven’t found a dashboard from an ESP that shows this number, but I expect it’s there somewhere.

Unsubscribes (0.2%)

The lower the better. If people are unsubscribing, it means you aren’t delivering the content they want. An unsubscribe is better than a spam complaint, but a high percentage of unsubscribes can harm an IP’s reputation just as easily. When I am onboarding subscribers from giveaways, I like to send out emails in blocks of 500-1000 and make sure to include the unsubscribe link front and center. I expect to have a higher rate of unsubscribes. This usually isn’t a problem as long as it doesn’t become a regular happening.

Spam Complaints (0.5% to not get into trouble with SES, but 0.1% is the expectation)

Complaints can kill an IP’s reputation and services who are concerned about the reputation of their IPs will have strict policies in place. They’ll have no problem suspending an account if the percentage is too high. Go higher than 1 spam complaint per 1000 emails and the reputation takes a hit.

One way to lower complaints is to include an unsubscribe link right at the top of the email.

Shared IPs vs Dedicated IPs

All this is fine and dandy because you’re following best practices and not doing anything to ruin the IP’s reputation. Right?


Unless you are paying for a designated or private IP, it’s not just you who affects the IP’s reputation. Other people are using this same IP and if they are playing fast and loose with best practices, they could ruin the IP (or a whole bunch of IPs).

If you want a real life example, let’s get in the wayback machine and visit the time when Bookclicker was a buzzing hive of activity.

Bookclicker, for those who don’t know, automated newsletter swaps. In theory, this was good. In practice, not so much. At that time Mailerlite was known to have lax standards. It was easy to get an account and they didn’t have strict restrictions on account activity. Because of their costs and features, every author and publisher signed up with them, including the authors and publishers who were most active on Bookclicker.

There are organizations that monitor IPs and if they see a history of activity that looks like spam, they will put an IP on a blacklist. Because there are filters in place intended to block most spam, some spammers have become creative in getting around those filters.

One practice has been labeled as Snowshoe Spam. Basically, this is the practice of sending out similar emails from different domains and IPs. If they have a list of 100,000 names, the spammer might break it down to 10,000 names per list and assign each list its own domain. So, if spam reports increase for an IP and the emails have similar content (links), it could be labeled as snowshoe spam. (Note: Smarter people than me are really good at creating algos to identify spam, because they don’t want the spammers to learn their secrets, they don’t share the how and why of identifying spam. Suffice it to say, if a similar email is sent from several different domains, they will trace it back to the IPs and blacklist the IPs.)

Can you guess where this is going?

Bookclicker, especially the larger lists that had an incredibly high volume of swaps, mimicked snowshoe spam. I might even go as far as saying it was snowshoe spam. The domains got traced back to IPs belonging to Mailerlite and the IPs got blacklisted. Those IPs were all shared, so anyone with the misfortune of sharing an IP with a high volume user on Bookclicker got blacklisted. Mailerlite called it their Author Problem. Mailerlite was also moving accounts with good stats to healthy IPs and IP groups. Free accounts and accounts with bad stats hung out in the unhealthy pools.

Just because you do everything right, doesn’t mean everyone else assigned to your IP is. This doesn’t mean you should run out and get a dedicated or private IP. Reputation is an odd duck and takes a lot of things into consideration. Sharing an IP means everyone works to build the reputation and unless you have a list with well over 100,000 individuals and are sending out a campaign at least once a week, it will be more difficult to maintain a good reputation.

What you can do is look for an ESP that has strict policies regarding bounces, unsubscribes, spam complaints, and even open and click rates. Mailerlite had to tighten up their policies in the aftermath of the Author Problem, but I’m not convinced they have done all they could.

Amazon SES has a pretty strict set of policies and has no problems putting an account on suspension before it can do irreparable harm to an IP or IP group.

When Mailerlite first hit the Spam Blacklist, I did some research. I actively looked for an ESP that had strict policies and enforced them. Unfortunately, I couldn’t find a list anywhere on the internet. Instead, I read between the lines and looked at their approval process. The easier their approval process, the more likely they were to have unhealthy pools.

In my searching, I also found a correlation between cost and deliverability. The ESPs with the best deliverability rates tended to be more expensive and known for having accounts jump through several hoops before approved.

Delivery Rate & Deliverability

Are you understanding why your IP is so important now? The IP reputation determines the fate of your campaign and whether your readers see it or not. You can find a decent breakdown of the more poular ESPs at this site I want to point out that Mailerlite and Mailchimp took a hit in Feb of 2020. That was about the same time we heard about Bookclicker being sold. This is purely conjecture, but Bookclicker’s popularity coincides with the drops in deliverability and might have helped play a significant role in contaminating the IP Pools.

The reputation determines the deliverability of a campaign. You could be doing everything right, but happen to be part of a crappy IP or IP group and readers aren’t getting your emails at all. Worse, you don’t know this is happening either because you can’t know for sure where the email landed if it made it past the front gate. It won’t matter how brilliant or great your newsletters are if your list doesn’t see your campaigns.

Delivery Rate

If someone asked what a delivery rate is and why it’s important, could you answer? If you can’t, don’t worry, I have an answer for you. It’s the percentage of emails that are actually sent. Delivery rate doesn’t care where those emails end up, only that they don’t bounce. To get the percentage, we use some basic math. First, you take the number of emails sent, subtract the number of bounces (both hard and soft), then divide that number by the total number of emails sent. For the math challenged among us (and I am definitely one of those), I’ll use some simple numbers for an example.

Let’s say I send out 100 emails. One (1) email is a hard bounce and two (2) emails are soft bounces. So, that’s 100-3=97. Then I divide 97 by 100 and get .97 or 97%.

But why is this number so important? It’s not in the scheme of things. We think it is because it’s the number that all services show, but it really doesn’t show us the data that gives us a better idea about the health of our newsletter. 

It can also be a good way to check the health of your IP or IP group. If the delivery rate has a significant drop between campaigns, it might mean you are getting more hard bounces and some providers are putting up a do not enter sign for the IP. If this happens, I recommend you ask your ESP to move your account to a new server with a healthier IP or IP group.


If delivery rate is the percentage of emails that actually get past the ISP’s front gate, deliverability is the likelihood of a reader actually seeing that email. ESPs and self-hosting with SES doesn’t have any way of showing deliverability. If you have a clean list, you probably have a high delivery rate and believe your readers are seeing all your campaigns. However, this might not be the case. Providers take the reputation of the IP into consideration when they decide where the email goes.

Best deliverability, your email hits your readers’ inboxes and they are given the opportunity to open it and interact.

Okay deliverability, your email hits their promotion tab and the opportunity to see, open, and interact with your email is significantly lowered.

Bad deliverability, your email is shunted to the spam folder. There is still an opportunity to see the email, but the readers have to do some digging.

Worst or no deliverability, your email never makes it anywhere near your readers’ inboxes, promotion tabs, or spam filters. The email never gets through the host’s filters and is either quarantined or labeled a hard bounce. 

I made the move from Mailerlite to self-hosting. Prior to that, I sent out an email explaining the move and including an unsubscribe link right at the top of the email. I also only sent that email to active subscribers. Or at least active subscribers according to Mailerlite.

Once I made the move and sent out a “welcome to my new home” email, some interesting things happened. First, I ended up bringing over 850 subscribers based on some strict criteria. Opened 3 of the last 5 emails sent and clicked at least once. My open number skyrocketed, nearly doubling (I ignored the rate because the total number of subscribers changed) and my click rate jumped to. (I improved my click to open rate just by jumping from ML to self-hosting.) However, my unsubscribe rate also jumped (not much, but I expected none and ended up with 5 plus 1 complaint).


Because I picked my most active readers I expected the percentage to go up, but I didn’t expect the actual number of opens to improve. When I compared the segment I moved with the first campaign, the numbers all improved with self-hosting. Unsubscribes and complaints went up and while unexpected, they were still within a healthy range. The only explanation I can figure out is that my IP reputation also improved from the ML mailing to the Self-hosted mailing and so did my deliverability. My emails aren’t being sent to the purgatory of the promotions tab, but sitting happily in the paradise of the inbox.