Email deliverability refers to how successfully your emails reach your subscribers’ inboxes—not just their mail servers, but specifically the folders where they’re most likely to see and engage with them.

Achieving high deliverability is essential to getting results from your email marketing. Even well-designed campaigns will underperform if they land in spam folders.

In this article, we’ll explain the difference between email delivery and deliverability, what affects inbox placement, and how to protect your sender reputation.

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 does it go 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).

Note that emails sent via Flodesk—or any email marketing provider—are promotional/marketing emails by nature, even if you don’t promote any offers in your actual newsletter, as the email is sent via an email marketing platform.

Email service providers (ESPs), such as Gmail, Yahoo, and Outlook, use various filters to evaluate incoming email.

They typically ask:

• Is this email safe?

• Do people want to receive this email?

• Does this person want to receive it?

If the answer is “yes” across the board, the email goes to the inbox. If not, it’s filtered out.

Key factors that affect deliverability include:

• Sender reputation

• Subscriber engagement

• Content quality

• Sending consistency

• Authentication status

Your sender reputation is like a credit score for your domain. Mailbox providers assign a reputation score based on your email history, but the scoring criteria are not public.

Sender reputation is influenced by:

• Open and click rates

• Spam complaints

• Bounce rates

• Sending consistency

• Authentication (DKIM, SPF, DMARC)

A strong sender reputation increases the likelihood that your emails will land in the inbox.

Subscriber behavior directly affects your sender reputation.

• Opens and clicks

• Replies to your email

• Moving your email from spam to inbox

• Adding you to contacts

• Ignoring emails over time

• Marking emails as spam

• Deleting without opening

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 their interest in joining 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.

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 matters. Sudden changes in sending volume, frequency, or domain can trigger spam filters.

• Send at least once per month to stay relevant (sending twice a month or weekly is even better!)

• Don’t suddenly increase your sending list size. 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.

• When rebranding or changing domains, warm up your new domain

• Gradually increase send volume, especially if you haven’t emailed in a while

• Avoid sending a high-volume campaign to your full list after a long pause. Instead, send in small batches starting with your most engaged segments.

• If you're about to send more emails than usual to your list, 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 if the email ends up in their spam folder, ask them to move it to their inbox.

Important: 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.

Learn more about warming up a new sending domain

Your email content can trigger filters, especially if mailbox providers are unsure about your domain reputation.

• Avoid link shorteners (e.g., Bitly)

• Always use HTTPS links

• Don’t use misleading subject lines

• Avoid aggressive sales language

• Include meaningful text (don’t rely on images alone)

• Ask subscribers to reply, add you to contacts, or move your email to their inbox

Learn more about how your content affects email deliverability here.

Starting in 2024, Gmail and Yahoo require bulk senders to meet new email authentication standards. You must:

• Use a custom sending domain

• Set up SPF and DKIM

• Configure a DMARC policy on your root domain

• Keep spam complaints low

By following these best practices, you can improve the chances of your emails reaching the inbox and achieving better results from your email marketing.