Validation of email addresses to protect against spam bots on the site

E-mail is still one of the most important and effective elements of online business and marketing and is the most effective channel for generating revenue. Therefore, for any online business and website owners, it is important to be sure that it is the owner of the email who used it to register / subscribe, so that the user uses his real email address.



There are several important reasons for this.

Firstly, it is important for recovering a forgotten password, for example: the user made a typo in his email address, after a while he used the password recovery function and cannot get a new password.

Secondly, this user will not receive your email notifications.

Thirdly, the user whose email was used by the spammer to register / subscribe will send your newsletter to spam. In the future, spammers can use this email to send spam, brute force, etc.

The use of such emails for marketing mailings and other email newsletters can carry certain risks for the site owner and increase the risks of adding DNSBLs to the lists, various blacklists, and increase the likelihood of spam and other emails in your folder. Increase your budget expenses for mailing to fake addresses or to addresses whose owners were compromised by spammers.

To avoid or reduce risks to a minimum, before mailing you need to check the list of email addresses.

Recently, we launched a check for the existence of email addresses, which checks whether such an email address exists or not. It uses MX records of the domain of the email address and connects to the mail servers (via SMTP, and also simulates sending a message) to make sure that the mailbox really exists for this user / address and that it can receive mail.

This scan solves several problems at once, reduces the likelihood of skipping spam and allows users to check their users' emails. To verify users, you can use the API method https://cleantalk.org/help/api-spam-check .

Sample API response result for https://cleantalk.org/blacklists?record=mattressfg%40gmail.com

{"data":
            {"mattressfg@gmail.com":
                      {"appears":1,
                      "frequency_time_10m":0,
                      "spam_rate":"1",
                      "frequency":"8",
                      "frequency_time_24h":1,
                      "updated":"2018-03-26 00:26:48",
                                                  "exists": 0, 
                      "frequency_time_1h":1}
            }
}




At the moment, we use this tool only to improve the definition of spam and check all email addresses that have had spam activity in the last 10 minutes. For verified addresses, a flag is set in the database, which is taken into account in further spam filtering and the API response.

“Exists”: “1” - exists
“exists”: “0” - does not exist
You can summarize the results, the proportion of non-existent email addresses in the spam mailing list is 25.34%.

We collect information about spam IP / email addresses from more than 237,000 websites. The base of email addresses contains more than 10 095 239 email addresses. And in our immediate plans, check all the emails in the database and run a check on all the email addresses that are processed by the service.