Function: Fix Email - Replace Email within <> of a String

I recently ran into a situation where I needed to update the From header of an outgoing email in PHP. Specifically, the header string contained a name and an email address wrapped in angle brackets, such as:

John Smith <oldemail@example.com>

The email data I was working with was stored inside an array structure (for example, $email['headers']['email']). My goal was to replace the existing email address inside the angle brackets (< >) with a new one while keeping the display name intact. To achieve this, I wrote a small helper function that uses regular expressions (preg_replace) to locate whatever text exists between < and > and substitute it with the new email address. This way, the function preserves the original formatting and any display name while seamlessly swapping in the updated address.

Here’s the function:

function fix_email($fromHeaderString, $newEmail) {
    return preg_replace('/<[^>]+>/', "<{$newEmail}>", $fromHeaderString);
}

The regular expression inside preg_replace is the key to making this work:

• / … / – the forward slashes are just the delimiters that wrap the regex pattern.

• < – matches the literal opening angle bracket.

• [^>]+ – this means “one or more characters that are not a >.” In other words, it captures everything inside the angle brackets, up until the closing bracket.

• > – matches the literal closing angle bracket.

So together, the pattern /\<[^>]+\>/ looks for any email address (or text) enclosed in < >.

Then, preg_replace replaces that entire match with a new string:

This ensures that whatever was originally between the brackets gets swapped out with the updated email address, while leaving the rest of the header (like the display name) unchanged.