Email Verification Parameters
Email Syntax Check
Parameter syntax
At the first stage, we check whether the email address is written correctly according to the RFC 5321 (SMTP) standard. The system validates the structure of the address — presence of the "@" symbol, correct domain zone, and valid characters. If the syntax is invalid, further verification is not performed, as such an email address is already considered invalid.
Whitelist and Blacklist Verification
Parameters whitelist and blacklist
Whitelist and blacklist settings help manage which domains are trusted or blocked. The whitelist includes domains that are explicitly allowed and trusted. The blacklist includes domains known for spam or malicious activity. On this demo page, both parameters are always set to false, but in your account you can define custom lists for each plan. Read more at demailify.com/en/about#whitelist-and-blacklist
MX Record Check
Parameter mx
MX (Mail Exchange) records are DNS entries that specify which mail servers are responsible for accepting emails for the domain. Valid MX records mean the domain can receive mail. If they are missing or misconfigured, the domain has no functional mail server, and verification stops at this stage.
DNS Records: SPF, DKIM and DMARC
Parameter dns (spf, dkim, dmarc)
These records are responsible for email authentication and security:
- SPF (Sender Policy Framework) — defines which mail servers are allowed to send emails on behalf of the domain, helping prevent spoofing and unauthorized sending.
- DKIM (DomainKeys Identified Mail) — adds a digital signature to each outgoing message, confirming that the email was genuinely sent from the declared domain and that its content wasn’t altered.
- DMARC (Domain-based Message Authentication, Reporting and Conformance) — combines SPF and DKIM, specifies how to handle messages that fail authentication, and enables domain owners to receive reports about spoofing or phishing attempts.
Temporary Email Detection
Parameter temp
Temporary email addresses (also called disposable emails) exist only for a short time, such as 10 minutes or an hour. They are commonly used for anonymous registrations or to bypass verification. We cross-check the domain against a comprehensive list of known temporary email services to protect your platform from low-quality or fraudulent sign-ups.
Deliverability Check
Parameter deliverable
Even if DNS and MX records are valid, a specific mailbox might still not exist. At this stage, the system simulates sending an email to determine whether the mail server accepts the recipient address. If the server reports that the mailbox is unknown, the address is marked as undeliverable.
Catch-All Domain Detection
Parameter catchall
Some domains are configured as catch-all — they accept all emails sent to any address under the domain, even if the mailbox doesn’t exist. Technically, the email is delivered, but it’s unlikely to be read by the intended user. Identifying catch-all domains helps you maintain accurate deliverability statistics and clean mailing lists.
Overall Email Validity
Parameter valid
The “valid” parameter summarizes all previous checks — syntax, lists, DNS, MX, temporary address detection, deliverability, and catch-all results. If all checks pass successfully, the email is considered valid (true). This parameter does not include domain age (age) or main site presence (http), which are explained below.
Domain Age
Parameter age
Domain age is an important trust factor. Young domains are often used for temporary or spam projects. Checking the domain’s registration age helps estimate reliability — the older the domain, the higher the trust. For example, you may allow only addresses from domains older than 5 years.
Main Website Presence
Parameter http
A working main website on the domain indicates a legitimate project or organization. If the main site is missing, the domain might be used only for email routing or disposable mailboxes. Checking the “http” parameter helps identify trustworthy domains and filter out suspicious ones.