The email validation glossary covers everything from spam and APIs to blacklists and bounce rates. Learn these key terms to improve your email management and protect yourself from online issues. Explore the world of email more effectively!

Email validation has been extensively discussed, along with the reasons why it is so crucial. Its advantages are undeniable for email marketers and anyone conducting any type of online business. We will do our best to define some of the most commonly used terms in connection with email validation today. So, if you ever get confused with the terminology, this resource is always available to assist you.

Let's start with the email validation glossary.

Spam emails

"Spam emails" are unwanted messages sent in bulk to many people. Some users mark them as "spam" when they consider them unsolicited emails. These "spam" marks help email service providers (ESPs) improve their filters and prevent similar messages from reaching recipients' inboxes.

Application Programming Interface (API)

An API acts as a link between two programs, allowing one to obtain data from the other and present it. It is a piece of software that serves as an intermediary. The API makes a call to the other program, makes a request, and provides specific data. With the help of the email validation API from Valid Email, you can instantly verify your subscribers.


If you work in email marketing, this is the list you most want to avoid. A bounce occurs when blacklists prohibit domains, IP addresses, or email addresses they don't trust. Your emails will not reach your subscribers' inboxes if you have a disorganized email list, which could put you on a blacklist. If your email address appears on the blacklist, Internet service providers (ISPs) and email service providers (ESPs) will stop accepting your emails.

Bounce Rate

The bounce rate is a metric that measures the frequency with which an email you send bounces or fails to be delivered to the subscriber. A high bounce rate indicates that the email list needs cleaning as it is disorganized. To get rid of invalid and temporary email addresses, it is common to turn to an email validation service, such as the one Valid Email offers.

Emails Catch-all

These types of addresses are mailboxes on a domain that will "catch" all emails sent to that domain, even if the address does not exist. Typically, businesses and government organizations set up catch-alls to ensure they do not miss any emails that may be trying to reach their domain.

Deliverable Email

When an email is sent to a correctly formatted address with an MX record, it is considered deliverable.

Temporary Email

Sometimes referred to as disposable email addresses, these are disposable emails that expire after a set period. People use them, as you might have guessed, for transient purposes like registering on forums, leaving blog comments, or downloading freebies. If you want to learn more about temporary emails, visit another of our blogs.

Email Deliverability

Similar to the bounce rate, email deliverability indicates the proportion of emails that reach the inbox. As it directly affects open and click-through rates, it is a crucial indicator in email marketing.

Email Validation

It is the process that checks if an email address exists and follows the correct format.

Email Verification

Email verification is a more complex process that checks if an email address belongs to a legitimate and active recipient.


This is an anti-spam technique to protect users from unsolicited emails. Any email sent by an unknown sender will be initially rejected by the recipient's mail server. Additionally, it will instruct the sender to resend the email in a short time. Until the recipient accepts or rejects it, their mail server will continue trying to send the email.


An "opt-in" strategy refers to an approach in which users must explicitly confirm their interest or desire to receive emails before their email addresses are considered valid or messages are sent to them. This strategy is essential to ensure that email addresses on your contact list are legitimate, and recipients genuinely wish to receive your messages.

MX (Mail eXchanger) Record

Your emails will be delivered as a result of a Domain Name System (DNS) record. Any email is forwarded by the MX record to a specified mail host, indicating the appropriate location for the email to be sent.

Role-based Emails

These emails are owned by a job title or a team of individuals within a company. They typically have formats like sales@, info@, team@, or contact@, so you can quickly identify them.

Spam Traps

Abandoned and recycled email addresses are used in spam traps. Blacklist providers and email service providers (ESPs) use these addresses as bait to catch spammers. They don't actually belong to anyone, and their sole purpose is to lure spammers.

Toxic Domains

Abuse, spam, and bot-sent emails are common in toxic domains. You should refrain from sending emails to any of their valid addresses that have a "toxic" flag, according to our email experts.

SMTP Bounce Codes

The Simple Mail Transfer Protocol (SMTP) is the protocol known as SMTP. They are codes that various mail servers send to indicate why they did not accept the emails you sent. They are crucial for finding out why your emails bounced. To determine the cause of your bounces, professionals from your email validation service may request these numbers.


A whitelist is a list of people who have been given permission to join. It indicates that your domain, IP address, and email address comply with best practices for email marketing. Therefore, your emails will reach the inbox.


When "conversions" are mentioned in the context of marketing, it refers to specific actions that a business or marketing professional expects email recipients to take as a result of receiving an email. These actions are typically crucial to marketing goals and can vary depending on the campaign's purpose. Some examples of important conversions might include:

  • Purchasing a product or service.
  • Registering on a website or platform.
  • Downloading a resource, such as an eBook or a report.
  • Subscribing to a mailing list or newsletter.
  • Participating in an event or webinar.
  • Completing a contact form.
  • Sharing content on social networks.
  • Completing a survey or providing feedback.

The goal is for the email recipient to take a specific action that is beneficial to the business or brand. Tracking these conversions is essential for measuring the success of an email campaign and adjusting the marketing strategy accordingly.


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