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How to Understand Email Deliverability

Why are my emails bouncing?

When an email cannot be delivered to an email server, it’s called a bounce. It’s almost impossible to predict whether an email will bounce because, in part, different internet service providers (ISPs) bounce email messages based on their own rating systems and definitions, which are constantly changing.

Even so, if your emails bounce, there are things you can do to minimize the problem. What’s recommended depends on the type of bounce.

Hard bounces

A hard bounce indicates a permanent reason an email cannot be delivered. There are two common reasons an email may hard bounce:

  • The recipient email address doesn’t exist or is misspelled.
  • The recipient email server has completely blocked delivery.

To avoid a hard bounce, we recommend keeping your list up to date and routinely cleaning your list to remove invalid email addresses.

In some cases, a valid email address will hard bounce because it’s been blocked by the recipient, a firewall, or a spam filter.

Soft bounces

Soft bounces can be attributed to many reasons, but generally indicate a temporary delivery issue that will usually resolve itself in time. The email platform we use will attempt to deliver the email seven times over a 24-hour period. If not successful, it will then mark the email as a hard bounce.

One of the best ways to avoid soft bounces is to ensure you have recipients’ permission to send them emails.

Before your first mailing is sent, reach out to everyone on your list and tell them to expect your email. Some first-time emails may be diverted to a recipient’s spam, junk, or promotions folder (in Google). If that is the case, then ask recipients to move your email to their inboxes. Your future emails should then be delivered as desired.

Why are my emails ending up in spam or junk folders?

Emails you send to recipients who have included you in their list of contacts will likely make it into their inboxes. But even legitimate emails sent to first time recipients (cold emails) can get trapped in spam and junk filters because of issues you may not have considered, like your sending name or email address, the subject line, or the message content.

Sending name or email address

You can lessen the chance your email will hit spam or junk folders by using a verified domain name—like,—rather than a free email service like Gmail, Yahoo, or Outlook.

Subject line

If a significant number of recipients are suspicious of your emails and mark them as spam, then email clients may start to block your emails delivered to other recipients using the same email client, and deliver emails directly to the spam or junk folder.

To avoid this problem, avoid clever subject lines and opt instead for being clear and direct.

There are also some subject lines features that may cause an email to go directly to a spam or junk folder. To minimize this happening to your emails:

  • Don’t write your subject lines in all caps.
  • Avoid using exclamation marks.
  • Steer clear of trigger words.

Why are recipients not receiving my emails?

There are three general reasons why recipients may not be receiving your emails:

  • They are bouncing.
  • They are being sent to the recipients’ spam or junk folder.
  • Either your or their Internet Service Provider (ISP) or email service provider is blocking your emails.

If you’ve confirmed that your emails are not bouncing or landing in your recipient’s spam or junk folder, then the issue is probably with either your or your recipient’s ISP.

Companies that make it possible for you to connect to the Internet are called ISPs (examples include Comcast, Verizon, and Optimum). Many of these same companies are also email service providers, but not all email service providers are ISPs (examples include Gmail, Yahoo, and Outlook).

Different ISPs have different ways of trying to prevent spam, malware, and viruses from getting into your recipients’ inboxes, and it’s possible that you and/or your recipient may need to contact your respective ISPs to solve the problem.

In the meantime, you might want to ask your recipient to:

  • Check their spam or junk folder.
  • Add your email address to their whitelist.
  • Check their computer’s firewalls and filters to see if your email is being identified as spam.

Why is an email showing as invalid?

We pre-validate emails uploaded into our system. That means we send out a ping to the email to make sure it connects. If it doesn’t, it’s marked invalid. 

The most common issue with invalid emails is typos in the address. Ensure you’ve got the name of your recipient and all other components of their email addressed spelled correctly. Check for missing or added letters in the recipient’s name, extra spaces, misspelled domain names, and misplaced @ marks.

Other common problems include:

  • The recipient has changed their email address and either deleted, or it was rendered inactive because they no longer use it.
  • The recipient who used a work email address was either promoted or fired and their email address was either changed or deleted.
  • The domain, server, or provider is dead. Whichever it may be, the result is your email can’t get through because it can’t be delivered.

Why do some recipients say “unsubscribed?”

If you received an unsubscribed notification, it’s because a recipient no longer wants to receive emails from you. They have likely clicked the unsubscribe link in your email.

When is the best time to send an email?

The short answer is it depends.

If you search the Internet for the best days and times to send, you’ll find a range of recommendations that will often contradict one another.

Our best advice is to test what works for your audience, but if you are looking for a place to start, then try the middle: middle of the week (Tuesday, Wednesday, Thursday) and middle of the day (10 a.m. – 2 p.m.)

Once you find what works best for you, continue to send your emails on that same day and time. Your recipients will come to expect to receive your emails and will look forward to them.

How are email opens tracked?

HTML emails, as opposed to plain text emails, can make use of tracking software that adds to your email an invisible image called a tracking pixel that is displayed when the subscriber opens your email. When that image is downloaded from the web server, the email is recorded as being opened.

It’s possible that not all emails will be tracked.

  • If the recipient is selecting to only use plain text, then neither opens nor clicks can be tracked.
  • The recipient’s email client may not be able to display HTML emails with images, or the option may be turned off.
  • The recipient may choose to read HTML emails but not to display images.
  • The recipient may have added a browser extension that alerts then to the presence of a tracking pixel and they choose to either delete or not open the email.

How do I export my list from my current email program?

We’ve developed a separate document providing instructions for exporting your mailing list from a large number of the most often used CRM. You can access that document by clicking here.

What is an open rate?

The open rate tells you the percentage of recipients that opened your email. To find your open rate, use this calculation:

Subscribers who opened email/Total number of recipients – Bounces = Open Rate

A good email open rate, which will vary by industry, is an indication that your subject line was able to spark enough interest that your recipients wanted to read your email. It can also tell you how much your recipients look forward to receiving your emails.

What is a click through rate?

Also known as a “click rate,” the click through rate (CTR) is a measure of how many people have clicked something in a specific email. Recipients can click on a hyperlink, an image, or a call to action. You can calculate your CTR this way:

Emails clicked/Emails sent – Bounces = Click Rate

The CTR is an important metric because it can tell you whether you are connecting with what your recipients want. A high CTR means what you are sending is relevant and valuable to them. A low CTR means you have a chance to send different information or retarget your audience.