You can use default magento core email to send the custom mail in magento.

$body = "Dear User,
 If you have an issue in magento contact me 'gotechsolution1@gmail.com'";
 $mail = Mage::getModel('core/email');
 $mail->setToName('Gotech');
 $mail->setToEmail('gotechsolution1@gmail.com');
 $mail->setBody($body);
 $mail->setSubject('Send Custom Email');
  //$mail->setFromEmail('gotechsolution1@gmail.com');
 $mail->setFromName("User");
 $mail->setType('html'); // You can use 'html' or 'text'
 $mail->send();

If you want to set custom Email template path in magento click here

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