SMTP use in PHPMailer - php

Question

I am using the last version of PHPMailer to send emails from my web. I can send some emails without SMTP parameters, but i need to give the SMTP configuration to my object PHPMailer(). The functions that sends this emails are in the same file.
Why some emails could need SMTP configurations and not others?
Regards
function sendEmailWithoutSMTP(){
$bodyIntern = file_get_contents('emails/myemail.html');
$mailIntern = new PHPMailer(true);
$mailIntern->CharSet = "UTF-8";
try {
//Recipients
$mailIntern->AddAddress('myemail#myemail.com', 'My address');
$mailIntern->SetFrom('myemail#myemail.com', 'My address');
$mailIntern->AddReplyTo('myemail#myemail.com', 'My address');
//Content
$mailIntern->Subject = 'My subject';
$mailIntern->AltBody = '';
$mailIntern->MsgHTML($bodyIntern);
$mailIntern->Send();
} catch (phpmailerException $e) {
//echo $e->errorMessage();
} catch (Exception $e) {
//echo $e->getMessage();
}
}
function sendEmailWithSMTP($email){
require_once 'smtp/getsmtp.php';
$smtp= get_smtp($email);
$bodyClient = file_get_contents('emails/myotheremail.html');
$mailClient = new PHPMailer(true);
$mailClient->CharSet = "UTF-8";
try {
//Server settings
$mailClient->IsSMTP();
$mailClient->SMTPDebug = SMTP::DEBUG_OFF;
$mailClient->SMTPAuth = true;
$mailClient->SMTPSecure = $smtp["secure"];
$mailClient->Host = $smtp["host"];
$mailClient->Username = $smtp["username"];
$mailClient->Password = $smtp["pass"];
$mailClient->Port = $smtp["port"];
$mailClient->Timeout= 30;
//Recipients
$mailClient->AddAddress('myemail#myemail.com', 'My address');
$mailClient->SetFrom('myemail#myemail.com', 'My address');
$mailClient->AddReplyTo('myemail#myemail.com', 'My address');
//Content
$mailClient->Subject = 'My subject';
$mailClient->AltBody = '';
$mailClient->MsgHTML($bodyIntern);
$mailClient->Send();
} catch (phpmailerException $e) {
//echo $e->errorMessage();
} catch (Exception $e) {
//echo $e->getMessage();
}
$this->sendEmailWithoutSMTP();
}

Answer 1

PHPMailer has several different ways of sending messages.
First of all there is the default, which uses PHP's built-in mail() function behind the scenes. This does not use SMTP, but hands the message to a sendmail program using a path set in your php.ini file. This sending method does not require any SMTP setup, and SMTP-related params (e.g. Username, Host) will just be ignored, but it does require that you have a local mail server.
isSendmail() is like a manually-constructed equivalent to PHP's built-in function, but it gives you a bit more control if you are using some unusual local mail server. Generally you should not use this.
If you call isSMTP(), it will try to use SMTP directly, and all of the SMTP parameters will be used. Even if you do have a local mail server, this is the recommended route because it's faster, safer, and easier to debug. If you need to send through a remote mail server (such as gmail), this is your only option.
So in your code, the first function is sending using mail(), and the second uses SMTP.