使用fsockopen验证邮箱有效性后，能否获取收件人姓名？

Great question! Let's break down what's possible with your current SMTP-based email validation setup, and the limitations you'll encounter.

Short Answer #

You cannot directly retrieve a recipient's real name (RECEIVER_NAME) using the SMTP connection method you’re currently using. Here’s why:

Why SMTP Won’t Return the Recipient’s Name #

1. SMTP Protocol Design
   The SMTP protocol is built for sending and routing emails, not querying user metadata. Even when you successfully validate an email exists (via RCPT TO commands), mail servers don’t include the recipient’s name in their responses—they only confirm the address is active.

2. Privacy & Anti-Spam Protections
   Nearly all major email providers (Gmail, Outlook, Yahoo, etc.) intentionally block any attempts to fetch user details via SMTP. This is a critical anti-spam measure to prevent bad actors from harvesting personal information. Even older SMTP commands like VRFY (once designed to verify users and return basic info) are disabled on almost all public servers today.

Example SMTP Session (No Name Returned) #

Here’s what a typical validation flow looks like with your method—note there’s no mention of the recipient’s name anywhere:

> fsockopen("smtp.example.com", 25, $errno, $errstr);
220 smtp.example.com ESMTP Postfix

> EHLO yourdomain.com
250-smtp.example.com
250-PIPELINING
250-SIZE 10240000
...

> MAIL FROM:<test@yourdomain.com>
250 2.1.0 Ok

> RCPT TO:<jane.doe@example.com>
250 2.1.5 Ok  // Only confirms the email exists, no name included

Are There Any Workarounds? #

It depends entirely on your use case:

• Internal Corporate Systems: If you’re working with an internal mail server (like Microsoft Exchange), you might be able to query user details via LDAP using the email address. This requires server-side permissions and is unrelated to your SMTP validation code.
• Third-Party Data Services: Some paid APIs claim to return user names paired with emails, but data accuracy varies widely, and you’ll need to comply with strict privacy regulations (like GDPR) when using these services.
• Test Emails (Not Recommended): Sending a test email and checking bounce messages won’t reliably return names, and frequent test emails will get your IP flagged as spam.

Final Note #

Stick to your current SMTP method for what it does best: validating that an email address exists. But don’t expect it to return any personal details like the recipient’s name—this isn’t a feature of the protocol, and modern security measures block any attempts to get this info via SMTP.

内容的提问来源于stack exchange，提问作者Surbhi Gupta