Detailed answer
No.
It checks a syntax constraint rather than mailbox ownership or delivery. Use a confirmation email when ownership matters and provide autocomplete=email for an ordinary contact address. Avoid overly narrow custom patterns that reject legitimate addresses. Test validation feedback and the full confirmation process independently.
Example
<label for="contact-email">Email</label>
<input id="contact-email" name="email" type="email" autocomplete="email" required>
Understanding the behavior
Email input validation checks a browser-supported address syntax, not whether the mailbox exists or belongs to the visitor. Successful delivery and ownership need a server-side verification process. Avoid treating a syntactically valid value as a verified identity.
Practical implementation notes
Test empty, malformed and plausible addresses, including the effect of required. If the application sends a verification message, keep the account's verification state separate from the input's validity state.
How to check it
Separate browser syntax testing from server delivery and mailbox ownership verification.
Expected result
Browser acceptance proves only a syntax constraint was satisfied.
Watch out: A syntactically valid address is not necessarily a verified mailbox.
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