phpMailer: Could not instantiate mail function

Question

I created a form that uses phpMailer to email the results to the website owner. Of course, before I add the owner's email address I use mine to test that the form works. When I use my email the form sends perfectly, however, when I use the owner's address it throws the error "could not instantiate mail function" and won't send the form. The error only occurs with email addresses associated with the owner's domain. Any idea why this could be happening?

If I type this into the command line it works fine:

echo 'test' | mail -s 'test' [email protected]

edit: I wasn't initially using SMTP, but it's now configured as shown below. The error message is now "SMTP Error: The following recipients have failed [email protected]" and the end result is still the same. It can e-mail to a number of gmail test addresses but has issue with the owner's [email protected]. Further, with SMTPDebug it's now producing the error "RCPT TO command failed: 550 No Such User Here" The owner's e-mail, however, works without issue when e-mailed through gmail, outlook, etc.

phpMailer code:

$mail = new PHPMailer();
$mail->IsSMTP();
$mail->SMTPDebug = 1;
$mail->Debugoutput = "error_log";
$mail->Host = "mail.mydomain.com";
$mail->SMTPAuth = true;
$mail->Username = "[email protected]";
$mail->Password = "XXXXXXXXXXXXXXX";
$mail->CharSet = 'UTF-8';
$mail->AddReplyTo($emailAddress);
$mail->SetFrom("[email protected]");

$mail->AddAddress($toAddress,$toName);

$mail->Subject = $emailSubject;
$mail->isHTML(true);
$mail->Body = $emailBody;
$mail->AltBody = strip_tags($emailBody);

// Attempt to send the e-mail       
if (!$mail->send()) {
    //error handling
}

what smtp are you using? also read your log file and issue > sudo tailf /var/log/maillog or if you're on a shared host, look at the main log file, i'm sure everything is combined into one or go to cpanel if you have that and go to read the mail log for additional errors. — unixmiah

unixmiah unixmiah · Accepted Answer · 2015-03-12T20:16:17

There are couple of things you should try and check with this particular error message:

Make sure you can use regular php mail() function. Create a blank page and use the php mail() to send a test email. If that works, maybe its your SMTP that's having issues with the particular user domain. Setup gmail SMTP or a different SMTP to send emails:

$mail->IsSMTP();
$mail->Host = "smtp.domain.com";

// optional
// used only when SMTP requires authentication  
$mail->SMTPAuth = true;
$mail->Username = 'smtp_username';
$mail->Password = 'smtp_password';

Can you share your phpMailer source for us to view?

phpMailer: Could not instantiate mail function

2 Answers