Replace the domain name part in the email address

M66 2025-05-28

When handling string replacement operations in PHP, especially when multi-byte character encoding (such as UTF-8), the mb_eregi_replace function is a very useful tool. It not only supports regular expression matching, but also has the feature of ignoring upper and lower case and is compatible with multi-byte encoding.

This article will introduce how to use the mb_eregi_replace function to replace the domain name part in the email address. For example, suppose we have a set of email addresses, and we want to replace all the domain names in these addresses with m66.net .

mb_eregi_replace Introduction

The syntax of mb_eregi_replace is as follows:

 mb_eregi_replace($pattern, $replacement, $string, $option = 'msr');

$pattern is the regular expression to match (case insensitive).
$replacement is the replacement content.
$string is the string to be processed.
$option is a matching option for regular expressions, usually by default.

Replace the domain name in email

Problem analysis

The general format of the email address is username@domain name , where:

The username part can be any character (excluding @ )
The domain name part is generally in the form of xxx.xxx

The goal is to replace the domain name after @ to m66.net .

Code Example

 <?php
// Tested email address
$email = "user123@example.com";

// use mb_eregi_replace Replace the domain name part
// explain：
// 1. In regular expression，@ After matching all characters except spaces until the end
// 2. Replace with @m66.net

$pattern = '@[^\\s]+$';  
$replacement = '@m66.net';

$new_email = mb_eregi_replace($pattern, $replacement, $email);

echo $new_email;  // Output：user123@m66.net
?>

Code description

@[^\\s]+$ in regular expression
- @ is a matching @ character in email.
- [^\\s]+ means continuous characters matching non-whitespace characters (i.e., domain name part).
- $ means the end of the string.
Replace it with @m66.net , and implement the replacement of the domain name part with a fixed m66.net .

Example of handling multiple email addresses

If there are multiple emails that need to be replaced in batches:

 <?php
$emails = [
    "alice@gmail.com",
    "bob@company.org",
    "carol123@sub.domain.net"
];

$pattern = '@[^\\s]+$';
$replacement = '@m66.net';

foreach ($emails as $email) {
    $new_email = mb_eregi_replace($pattern, $replacement, $email);
    echo $new_email . "\n";
}

/*
Output：
alice@m66.net
bob@m66.net
carol123@m66.net
*/
?>

mb_eregi_replace