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Email testing 101: How to test email deliverability

Sent. The best feeling ever after putting together a campaign, or crafting the perfect message? But will your email make it to their inboxes? If you think you lose sight of your message after hitting that send button, you’re missing out. Stick with us and dive into deliverability testing so you can see exactly how your message lands.



Deliverability is the ability to get your messages into your recipient’s inbox without being blocked or marked as spam. Without deliverability testing, you may miss issues that could prevent your messages from getting through. Poor deliverability means low engagement and low conversions. Keep reading for everything you need to know.

What is email deliverability?

Email deliverability is a sender’s ability to get their email into their recipient’s inbox. In other words, deliverability is a set of strategies and techniques that ensure your email messages land in your reader’s inbox. This is also known as inbox placement.

There are several factors that affect deliverability, these are some of the biggest:

  • Sender Reputation: The reputation of your domain and IP address plays a critical role in your deliverability.

  • Content quality: Mailbox providers use countless filters to scan incoming email messages for spammy or suspicious elements like strange or excessive punctuation, certain keywords, or poor formatting.

  • Email authentication: Email authentication protocols like Sender Policy Framework (SPF), Domainkeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting and Conformance (DMARC), help verify your identity as a sender and help identify and protect you against spamming or phishing attacks.

  • List Hygiene: The quality of your email list. Validate to ensure that typos and inactive addresses don’t affect your deliverability. Make sure your subscribers have opted-in to receive your emails.

When should I test my email deliverability?

What is an email deliverability test? Email deliverability testing is a combination of best practices pre-deployment testing, and seed list testing. The point is to ensure your emails land in the inbox regardless of mailbox provider, whether it be Outlook or Gmail. It’s essential to test your deliverability before sending a large volume of emails, like in an email campaign, newsletter, or product update announcement.

In addition, if you’re sending out a high volume of emails consistently over a specific period, track your logs and analytics to ensure your emails aren’t bouncing. If you notice an increase in bounce rates, re-test your deliverability. If you’re unsure where to start, check out Mailgun Optimize, our deliverability suite geared to prep your emails for sending today.

What are five key factors that affect email deliverability?

Email deliverability is complicated because a lot of elements contribute to good deliverability. The list is long, from SPF records to targeted messaging and email marketing. Here are five of the most influential factors:

  • Email authentication: Authentication protocols are your “ID card” that tells ISPs you are who you say you are. If you’re unfamiliar with SPF, DKIM, DMARC, and BIMI, this is a great place to improve your deliverability.

  • Sender reputation: ISPs rely on your sender, IP, and domain reputation to determine whether or not to place your email in your reader’s inbox. Remember, email reputation is hard to maintain but easy to flub up. Just like deliverability, there’s not any one thing that ISPs use to gauge your sender reputation. However, keeping your email bounces low and reader engagements high is a good start.

  • Email bounces: Email bounces also affect how ISPs view your sender reputation. While a few bounces won’t reflect too poorly on your reputation, a high bounce rate can send red flags to ISPs and land you in the spam folder or, worse, on a blocklist.

  • Mailing list hygiene: Maintaining your email list hygiene means regularly evaluating your email list and removing invalid email addresses or sunsetting disengaged users. Keep your email list clean to reduce email bounces and increase user engagement.

  • Have a comprehensive email delivery infrastructure: Not sure where to start? ESPs like Mailgun can boost your deliverability by ensuring proper authentication protocols and sending infrastructure.

How can I test email deliverability?

Email deliverability may sound like an abstract concept, but it’s actually something you can monitor and test.

Here are a few types of testing to keep your email deliverability high:

  • Authentication testing: Did you set up your SPF, DMARC, BIMI, and DKIM records correctly? Don’t leave this up to chance. Authentication testing ensures you’ve configured your outgoing mail server correctly to send emails.

  • Content testing: Send e-mails that your recipients want to engage with. Messages that don't render correctly are often passed over. Check out how Email on Acid’s pre-deployment testing tools can help you perfect your email content before hitting send.

  • Seed list testing: With seed list testing, a sender can get conclusive inbox placement results, taking the guesswork out of how an email is performing. This testing helps determine how your email will land across different email clients. With our seed testing Inbox Placement tool, Mailgun can be your one-stop shop for email sending.

What are some key tools to test email deliverability?

The Sinch family has you covered in terms of deliverability testing. Check out some of our tools and functionalities below:

Mailgun Optimize is our suite of deliverability tools guaranteed to help you land in your reader’s inbox, and it has some standout features that are useful to test the deliverability of your messages.

  • Inbox Placement: Don’t leave the performance of your email up to chance. Get a sneak peek at whether or not ISPs will place your email in your reader’s inbox before you even hit send.

  • Campaign Pre-check: Email content and design are crucial for your deliverability. See how Email on Acid’s Campaign Pre-Check functionality can help you check hyperlinks, spelling, mobile responsiveness, and more.

Final thoughts

Email deliverability isn’t a mysterious metric, it’s something you can plan for, monitor, and test to improve your sender reputation and email delivery. It’s also not something you have to build alone. Partnering with a good ESP that has deliverability tools and support will take you most of the way. Want to learn more? Then check out our deliverability services and the awesome account managers that will give you the edge you’re looking for with your email program.

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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