Member Avatar for Ankur_8

This is the error
Warning: mail(): Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set()

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Quick summary for : that PHP warning means your script tried to hand the message off but there was no mail agent listening on your machine. On Windows PHP will connect to an SMTP listener; on Unix-like systems it normally calls the local sendmail program (or the path set in php.ini). See the PHP docs for how PHP hands mail off. (PHP mail configuration).

Three practical ways to fix this (pick one):

  • Run a local SMTP agent and point PHP at it — XAMPP bundles Mercury on Windows and you can start/configure it from the control panel; hMailServer is another lightweight Windows MTA you can install. (XAMPP, hMailServer).
  • Use a sendmail emulator / sendmail_path so PHP can pipe messages to a program that relays to an SMTP server (the common “fake sendmail” tools shipped with many dev stacks do this). (fake sendmail for Windows).
  • Skip mail() and use an SMTP library (recommended for production): PHPMailer or a similar library lets you connect with authentication and TLS/STARTTLS to any SMTP service. Example using PHPMailer below. (PHPMailer).

A minimal PHPMailer SMTP example:

<?php
use PHPMailer\PHPMailer\PHPMailer;
require 'vendor/autoload.php';
$m = new PHPMailer(true);
$m->isSMTP();
$m->Host = 'smtp.example.com';
$m->SMTPAuth = true;
$m->Username = 'user@example.com';
$m->Password = 'app-or-account-password';
$m->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
$m->Port = 587;
$m->setFrom('from@example.com');
$m->addAddress('to@example.com');
$m->Subject = 'Test';
$m->Body = 'Hello';
$m->send();

For local testing without sending real mail, use MailHog, Papercut or Mailtrap to capture outbound messages and inspect them instead of delivering. If you plan to use Gmail as the SMTP relay, note Google now requires OAuth2 or an app password for accounts with 2‑step verification — plain username/password access is blocked. (MailHog, Mailtrap, ).

Quick troubleshooting checklist: make sure the SMTP service is running, firewall isn’t blocking the port, php.ini changes are followed by an Apache/PHP restart, and check SMTP or sendmail logs for delivery errors. As and hinted, starting/configuring a local SMTP (or switching to an SMTP library) resolves this in almost every localhost case.

Recommended Answers

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Member Avatar for Member #120589

Do you have an SMTP server up and running? E.g. if you use XAMPP, it has "Mercury" installed, which you need to start.

Member Avatar for Dani

Looks like PHP's mail() function is trying to connect via SMTP, but it's either not installed or configured improperly.

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