How to Validate an Email Address for Typos, Syntax, Curse Words, and Other Rules | WhoisXML API

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How to Validate an Email Address for Typos, Syntax, Curse Words, and Other Rules

Posted on January 24, 2020
How to Validate an Email Address for Typos, Syntax, Curse Words, and Other Rules

Email marketing is without a doubt sound investment for companies. For every $1 spent on email marketing, the return on investment (ROI) can be as high as $32.28, according to DMA’s Marketer Email Tracker report.

The same study examined the respondents’ mailable list size, return rates, and delivery rates, and the findings are quite surprising. Some 55% of the respondents said there was a significant rise in their organization’s mailable list size, yet only 36% reported increased delivery rates. Also, 36% of the respondents said they encountered an increase in the number of returned emails.

Marketer Email Tracker report.

While on average about half of the respondents increased their open, click-through, and conversion rates, we can’t help but speculate whether these numbers can still be improved if email marketers were to find a way to decrease return rates while increasing delivery rates.

One method that can help organizations achieve these goals is by making sure that the email addresses in their databases are valid. Valid email addresses can dictate the success or failure of any email marketing campaign.

Email validation with the use of tools such as Email Verification API should, therefore, be a necessary process when launching a campaign.

What Is Email Validation?

Simply put, email validation is the process of verifying an email address’s validity and deliverability. Keep in mind that the end goal is for the owner of the email address to receive your marketing message in his/her inbox. The person’s next actions — whether to open the email and click on embedded links or not — depend on several factors, including the message’s quality, but this is a topic that warrants a separate post.

For this article, we focused on creating email address validation rules as a significant step toward improving open and click-through rates.

How to Validate Email Addresses

Tools such as Email Verification API make email validation less time-consuming and more accurate. You can integrate the API into your application or website so that it can validate email addresses in real time. It can also be tweaked to satisfy your organization’s validation requirements.

In this section, we explored different ways by which Email Verification API can validate email addresses.

Check Syntax

An email address should have this format:, where the local-part can be any combination of letters and numbers, and the is the company or email provider’s domain name. Both parts are case-insensitive.

Check for Common Domain Typos and Curse Words

Aside from checking the validity of an email address, email validation tools also let you know why an address is invalid. For instance, Email Verification API checks for the most common domain typos such as:

  • Gmail:,,,,
  • Yahoo! Mail:,,,,
  • Hotmail:,,,,

There are other common typos that can be checked with Email Verification API’s database of registered domains, and the tool lets users verify email addresses against all of them. The API can also be customized to check for curse and abusive words in the email address’ body.

Check If an Email Address Is Disposable

A useful email validation tool also provides insights into the trustworthiness of an address. Disposable email addresses, for instance, not only negatively affect your email marketing campaign; some are also fraudulent.

Users who sign up for disposable addresses are likely to ignore your messages as they may only be after free trial versions and other freemium features. They can, therefore, affect your open and conversion rates, ultimately rendering your email marketing efforts useless. Aside from that, cybercriminals also use disposable email addresses to perpetrate fraud.

Popular disposable email address providers include Mailinator, GuerillaMail, 10MinuteMail, Nada, E4ward, and others. Email Verification API is programmed to detect email addresses issued by these providers.

Check If an Email Address Is a Catch-All One

Marketers also need to be on the lookout for catch-all email addresses. Businesses typically create catch-all email addresses so they won’t miss out on any messages from customers. For instance, a potential client might send an email to instead of With a catch-all email address, your company can still receive an email even directed to the mistyped one.

While this works great for businesses, it won’t benefit marketers and may even result in hard bounces later on. Companies may accept your emails at first but might later on set parameters to reject them since catch-all addresses can also be used to screen unwanted messages.

Email Verification API is a practical way for email marketers to improve their deliverability rates while reducing email returns. Among other use cases, Email Verification API can be integrated into your website or application during the registration process so it can start prompting users to enter the appropriate addresses as soon as they get access to their accounts.

However, if you already have a list of email addresses that you want to validate, you can run up to 50,000 email addresses on Bulk Email Verification API to shorten the screening process.

For more information on how email verification can help in the discussed and other instances, feel free to contact us at .

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