Protecting and improving your deliverability can feel overwhelming, especially with the constantly evolving technologies that surround email in general. To help clear things up, we came up with some pointers about common deliverability mistakes and how to avoid them.

1. Improperly gathering subscribers

Gather subscribers in a very visible and intentional manner, not through ambiguous or illegal methods.

Purchasing, scraping, or sharing lists between organizations is not considered “permission-based” and is against our Permission & Privacy Policy. It’s also illegal in many countries and terrible for your deliverability overall. Furthermore, obtaining signups through means other than direct requests for consistent marketing mail will also hurt your deliverability. Great examples of these types of technically-legal-but-unhealthy practices are:

• Giveaways
• Gated content
• Adding contacts to more subscriptions than what expressly signed up for; i.e., they signed up for Monthly Newsletters but you added them to your Weekly Coupon Campaigns

When contacts sign up for marketing emails, your follow up behaviors should be explicitly in line with their motivation for signing up. They should get exactly the mail they expect; no more, no less.

Sometimes, old adages are true: an ounce of prevention is better than a pound of the cure. In the email marketing world, this means building a solid, permission-based list where your recipients have expressly opted-in to receive your emails. Believe it or not, having a subscriber base that not only knows that you are going to send to them, but actually looks forward to your emails will make a measurable difference in your deliverability metrics.

2. Sending marketing mail from a free domain

Send marketing content from an active email address with your organization’s domain, not from a freemail address.

Using a sender email address that has a domain other than your own can cause huge delivery problems. Similarly, using a free domain email address such as Hotmail, Yahoo, or Gmail is also a bad idea. This is because Yahoo, Gmail, and other inbox providers will automatically mark your emails as spam, or block them outright, if you send commercial or bulk emails from an email address at their domain.

Not only will sending from a private domain help prevent unnecessary problems like spam filtering, but your address will also be instantly recognizable to your recipients, increasing their likelihood of seeing and opening your emails. If you don’t own a domain, check out our Domain names and registrars article for information about how to buy one.

3. Sending without an authenticated domain

Set up DKIM and DMARC on your domain to verify your emails’ authenticity, before sending any emails from your account. Do not send without setting up email authentication first!

A large part of email deliverability comes down to taking every step possible to come across as a good, respectable sender in the eyes of inbox providers and your recipients. Authentication allows inbox providers to confirm the legitimacy of your emails. When you authenticate your domain, receiving inbox providers have verifiable information to cross-reference with your email campaigns and can more easily determine if your email is the real deal or fraudulent.

Many major inbox providers now require DMARC and DKIM authentication, at minimum, for anyone sending through an email service provider (ESP). When you send unauthenticated emails, these inbox providers will send your emails straight to spam or even reject them entirely. Over time, this can have a serious effect on your sending reputation. To prevent this, we strongly advise that all accounts set up DMARC and DKIM, at minimum. For more information about authentication, check out this article.

4. Using link shorteners or third-party links

Use links hosted on your own site or link to a landing page that contains third-party links. When possible, avoid using link shorteners or third-party links.

When considering the impact of links on deliverability, it is important to understand that the impact is different depending on whether you are using self-hosted links, link-shorteners, or third-party links. For instance, the use of link-shorteners (e.g. bit.ly) is a technique that is commonly used by spammers to hide the true nature of their spam / phishing URLs. This practice has caused widespread delivery / deliverability problems for legitimate senders who want to use link shorteners in marketing emails.

Receiving servers don’t just check the reputation of the sending domain, they also check the domains of all the links included in an email. During these checks, servers tend to be harsher towards suspicious links, especially when attempting delivery to B2B addresses (private, business domains), due to the security threat that links create. As a result, the safest policy is to use only self-hosted links in marketing emails (hosting the content on your own website, if possible). Since you can’t control the reputation for third-party domains, you can’t control whether it affects your ability to reach the inbox unless you remove its effect from the equation.

The safest way to include links in your campaigns is to self-host as many of the links as possible. If you must point to third-party sources, only use widely-recognized, reputable sites. You can also use Google’s Transparency Report to check links from sites whose reputation you’re not sure about.

5. Sending too small or large emails

Send focused emails with a good image-to-text ratio. Don’t send emails that are only an image and a link, or emails with excessive amounts of content.

The size of your emails can affect your delivery / deliverability, though its impact within the process is much lower than items like engagement and list-health practices. With that being said, for some inbox providers, having too little information in a marketing email can look suspicious. Emails with very little text and many images, or those simply composed of one large image and a linked text can be hallmarks of spammers or phishers. If you send emails like this, you can run the risk of your email being flagged as spam.

To prevent this, it is important to design your emails with a balanced image-to-text ratio so that your email makes sense and is engaging. This is especially important in case an inbox prevents some or all images from being displayed, something many companies do for security reasons.

On the other hand, some inbox providers view having too much information in a marketing email as problematic. While for the most part, this has less to do with looking like a spammer, it can still cause problems, as mailbox providers have limited storage space and have to put a limit on how much storage is taken up on their servers. Some inboxes may also clip your email if it becomes too long, which hides parts of your email until the recipient clicks to display the whole thing.

Other reasons to not have too much information in your campaigns:

1. Mobile Load Times: Mobile viewing of email is growing more and more common. Studies have shown that the amount of time users will wait patiently when viewing information is even lower on mobile devices than on desktop.
2. Reader Attention Span: We all know that subscribers have other emails to read and other things to do. You’ll want to keep that in mind so that you create engaging content that gets the point across quickly and efficiently.
3. Burying Important Content: If the content is a mountain of information to rummage through, most people will move on to something easier and more engaging.

A general best practice is to keep the entirety of the file size to less than 2 MB. This includes both HTML and images together. While the file size of your email doesn’t need to be a worry on a day-to-day basis, it is something to keep in mind.

6. Sending inconsistently

Send in a consistent, predictable manner to create expectation with your subscribers. Don’t send sporadically, inconsistently, or unexpectedly.

As is true for any marketing field, visibility is key, but what is often overlooked by email marketers is the role of expectation. Creating expectation within your subscriber base creates healthier engagement, which strengthens deliverability. Sending infrequently can cause forgetfulness in your subscribers, especially when so many other marketers are delivering content to their inboxes on a daily basis. Creating a consistent sending pattern (whether daily, weekly, or monthly, whatever suits your content / audience) will help build subscriber expectations and strengthen your overall visibility.

7. Burning out subscribers

Allow your subscribers to choose the type and frequency of content that they receive. Don’t burn them out by oversending promotional content.

As previously mentioned, it is important to send consistently and regularly, but it is also important to make sure that you are not sending too often for your subscriber base. This can vary depending on your industry and brand, but with some testing, you should be able to find a sending frequency that works for you and your subscribers.

One way that you can help identify this is by providing a Subscription Center for your subscribers, so that they can choose how often they want to hear from you and which types of content they want recieve. Giving subscribers greater control over their subscription relationship with you creates a friendly experience and helps protect them from receiving too much, which can cause them to completely jump ship.

You can also accidentally burn out subscribers by sending only promotional content. The constant strain of buy-from-me requests is exhausting, especially since they are getting it from so many other marketers as well. By sprinkling in fresh value content, such as campaigns simply highlighting the current tips and tricks in your industry, within your marketing strategy, your subscribers will be more inclined to organically support your company.

8. Not maintaining your audience

Don’t build and build your audience without cleaning out unengaged subscribers. Instead, send a re-engagement campaign and opt out any contacts who remain unengaged.

To inbox providers, low open rates are a clear sign that your recipients are not engaged with you, your brand, or your content. That lack of engagement becomes a major factor in the delivery of future emails and can even lead to your campaigns being blocked. Think of it as a snowball threatening to become an avalanche — low open rates mean that mailbox providers will aggressively filter future emails, which leads to even lower open rates, and in turn, leads to a further lack of engagement.

No matter the size of your audience, it’s important to consider the health and effectiveness of your contact list, especially if it’s a list that you’ve nurtured and grown over a long period of time. By continuing to send campaigns to contacts that consistently don’t open your emails, you could be damaging your sending reputation.

To avoid this, we recommend sending a re-engagement campaign to your contacts who haven’t opened your mailings in 3-11 months, depending on your send frequency. After you’re sent a re-engagement campaign, any contacts who have not engaged with your mailings in the last 12 months should be removed from your mailing lists completely. Be sure to continue doing this list maintenance every six months thereafter.

Removing old, inactive email addresses helps protect your reputation with inbox providers so that they know that you are a sender whose subscribers are interested in your contentand, therefore, should not be filtered.

9. Not monitoring response data

Use your Response data to craft a mailing strategy; don’t just send your campaigns blindly.

The Response data provided by ESPs is one of the greatest tools for protecting your deliverability, so it’s important to regularly check and act upon what you see there. We recommend checking your Response data on a weekly basis, at least.

We also recommend using the subject line and content split test features. Split testing can help you observe what types of content or subject lines your audience engages with more. Using these tools consistently over time allows you to continue refining and improving your campaigns to fit your audience.

You can also create engagement segments to learn more about your audience’s patterns. Depending on your sending frequency, create segments for 1 month non-openers, 3 month non-openers, 6 month non-openers, and so on. This will help you see when people typically get fatigued and allow you to create strategies to prevent that.