src/Mail/Message.php
public function addAttachment(string $file, string $content = null, string $contentType = null): MimePart
    {
        return $this->attachments[] = $this->createAttachment($file, $content, $contentType, 'attachment');
    }
public function addAttachment(string $file, string $content = null, string $contentType = null): MimePart
    {
        return $this->attachments[] = $this->createAttachment($file, $content, $contentType, 'attachment');
    }
public function addAttachment ( string $ file , string $ content = null , string $ contentType = null ) : MimePart { return $ this -> attachments [ ] = $ this -> createAttachment ( $ file , $ content , $ contentType , 'attachment' ) ; }
Adds attachment.

@param string      $file
@param string|null $content
@param string|null $contentType

@return MimePart
Adds attachment .