Email deliverability is an important measure of how successfully your emails are delivered to your subscribers' inboxes instead of being filtered to spam folders. After investing time and effort into your email marketing campaigns, you want your emails to be seen by the people you send them to. That's why deliverability is so important.

First, let’s look at what happens with your emails when you hit send on them in Flodesk. There are two important concepts that we need to discuss: email delivery and email deliverability.

When you hit send on your email in Flodesk or a subscriber starts your workflow, the email leaves Flodesk's servers and travels through the Internet. It then arrives at your recipients' (subscribers') mail servers. The recipient's mail server uses certain checks, and it either accepts or rejects your email.

Email delivery refers to when an email is successfully delivered to a recipient’s mail server. It accepts the message. A bounce occurs when an email is either not successfully delivered or is rejected by the recipient's email provider.

Learn more about bounced emails here.

Once your email is successfully delivered to your subscriber’s mail server, the next question is where it goes from there? Will it be delivered to your subscriber’s main folder? To the promotions tab? Or even to spam?

Email deliverability refers to the placement of an email after it is successfully delivered to the recipient’s mail server. Good email deliverability allows your emails to land in your recipient's primary inbox (including tabbed inboxes, such as Google’s Promotions tab).

Many things can influence whether your emails make it to the inbox or get stuck in the spam folder.

Generally, mailbox providers, companies that manage people's email inboxes, such as Gmail, Microsoft, Yahoo, etc., look at a few key things:

If the answer to all three questions is yes, the email goes to the inbox. If the answer is no for any of them, the email goes to spam. Mailbox providers typically rely on the sender reputation to make this decision.

Mailbox providers give your sending domain a reputation score, similar to a credit score. However, they never reveal exactly what your score is and why. They keep your score and the algorithms used to determine it private.

This score is heavily influenced by how the people you send emails to interact with them, also known as subscriber engagement.

How people respond to your emails—whether they open them, click on links, or mark them as spam—can make a big difference in where your emails end up.

You can take steps to encourage positive engagement and make sure your emails don't get marked as spam. These include, among other things:

When you move email marketing providers, only upload subscribers where you have verifiable proof of consent to email marketing and who were engaged with your emails on the old platform. Quality is much more important than quantity.

If you’re new to email marketing, consider enabling the double opt-in on your forms. This adds an extra layer of protection, and only subscribers who confirm they want to join your list will be added. If you see some subscribers haven’t confirmed their subscription yet, you can select them in bulk in Flodesk and resend them the double opt-in email again.

Regularly check for disengaged subscribers and remove them from your list. Engaged subscribers who are eager to receive your emails will boost your open and click rates, increase your sender reputation, and help ensure your emails are delivered to the inbox.

Consistency is key to email deliverability. If mailbox providers see a sudden change in how often you send emails, they may deliver them to the spam folder to be on the safe side.

If you're about to send more emails than usual to your list, proactively let them know about it. You can foreshadow when your next email will be sent and even tell them the subject line to look forward to. And should the email end up in their spam folder, ask them to move it to the inbox. Also, aim to send at least once per month to keep your sender reputation established.

Beyond your sending frequency, be consistent with your sending domain. For example, if you're rebranding your business and moving to a new domain, avoid sending a high volume of emails immediately from the new domain.

Similarly, if your domain hasn’t sent any emails in a long time (over six months), start sending slowly and to a small group of highly engaged subscribers first. And gradually increase the number of your recipients. By warming up your sending domain this way, you can establish a solid domain reputation and it helps with email deliverability overall.

Lastly, be consistent with your sending volume as much as possible. While your subscriber list dynamically changes as people join and leave your list, any sudden change in your recipient numbers could raise a red flag.

For example, if you usually send your weekly newsletter to 3,000 subscribers in your “newsletter segment”, avoid sending your next email campaign to your “All subscribers” segment of 7,000 subscribers. Instead, start sending in small groups, even if it means sending the same email in a few batches. Play it safe! Your sender reputation will thank you for it.

If your subscribers’ mailbox providers haven't seen enough consistent emails from you, see the previous section, they might use your email content to decide if your email is safe or not. Content they look at includes images, links, subject lines, email body. 


On the other hand, if they know you send a lot of emails and have a good sender reputation, they might not pay as much attention to your content.

Here are some things to keep in mind for your email content:

Learn more about how your content affects email deliverability here.

Last but not least,

Google and Yahoo have announced new sender requirements set to be enforced in 2024. These include

Adhering to the above guidelines and best practices can ensure better email deliverability, improving the chances of your emails landing in your recipients' primary inboxes.