I checked from your website. Your server is adding some things to the output, which neither comes from
X3, or the
PHPMailer application.
Did you disable the debugger option? Your server is adding this to the output, including some strange javascript at the end:
2017-06-13 12:35:50 Connection: opening to s58.hekko.pl:587, timeout=300, options=array (
)
2017-06-13 12:35:50 Connection: opened
2017-06-13 12:35:50 SERVER -> CLIENT: 220 s58.hekko.net.pl ESMTP Exim 4.86.2 Tue, 13 Jun 2017 14:35:50 +0200
2017-06-13 12:35:50 CLIENT -> SERVER: EHLO sabatek.pl
2017-06-13 12:35:50 SERVER -> CLIENT: 250-s58.hekko.net.pl Hello s58.hekko.net.pl [188.116.16.68]
250-SIZE 104857600
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250-STARTTLS
250 HELP
2017-06-13 12:35:50 CLIENT -> SERVER: STARTTLS
2017-06-13 12:35:50 SERVER -> CLIENT: 220 TLS go ahead
2017-06-13 12:35:50 CLIENT -> SERVER: EHLO sabatek.pl
2017-06-13 12:35:50 SERVER -> CLIENT: 250-s58.hekko.net.pl Hello s58.hekko.net.pl [188.116.16.68]
250-SIZE 104857600
250-8BITMIME
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
2017-06-13 12:35:50 CLIENT -> SERVER: AUTH LOGIN
2017-06-13 12:35:50 SERVER -> CLIENT: 334 VXNlcm5hbWU6
2017-06-13 12:35:50 CLIENT -> SERVER: aW5mb0BzYWJhdGVrLnBs
2017-06-13 12:35:50 SERVER -> CLIENT: 334 UGFzc3dvcmQ6
2017-06-13 12:35:50 CLIENT -> SERVER: am9hbm5hU2FiYXQyNw==
2017-06-13 12:35:50 SERVER -> CLIENT: 235 Authentication succeeded
2017-06-13 12:35:50 CLIENT -> SERVER: MAIL FROM:<info@sabatek.pl>
2017-06-13 12:35:50 SERVER -> CLIENT: 250 OK
2017-06-13 12:35:50 CLIENT -> SERVER: RCPT TO:<info@sabatek.pl>
2017-06-13 12:35:50 SERVER -> CLIENT: 250 Accepted
2017-06-13 12:35:50 CLIENT -> SERVER: DATA
2017-06-13 12:35:50 SERVER -> CLIENT: 354 Enter message, ending with "." on a line by itself
2017-06-13 12:35:50 CLIENT -> SERVER: Date: Tue, 13 Jun 2017 14:35:50 +0200
2017-06-13 12:35:50 CLIENT -> SERVER: To: info@sabatek.pl
2017-06-13 12:35:50 CLIENT -> SERVER: From: info@sabatek.pl
2017-06-13 12:35:50 CLIENT -> SERVER: Reply-To: Karl <karl@www.photo.gallery>
2017-06-13 12:35:50 CLIENT -> SERVER: Subject: =?UTF-8?Q?sabatek.pl_|_Nowa_wiadomo=C5=9B=C4=87_od_Karl?=
2017-06-13 12:35:50 CLIENT -> SERVER: Message-ID: <4a32b8a2c8807c6ffda0038faf19c5ee@sabatek.pl>
2017-06-13 12:35:50 CLIENT -> SERVER: X-Mailer: PHPMailer 5.2.10 (https://github.com/PHPMailer/PHPMailer/)
2017-06-13 12:35:50 CLIENT -> SERVER: MIME-Version: 1.0
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Type: multipart/alternative;
2017-06-13 12:35:50 CLIENT -> SERVER: boundary="b1_4a32b8a2c8807c6ffda0038faf19c5ee"
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: This is a multi-part message in MIME format.
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: --b1_4a32b8a2c8807c6ffda0038faf19c5ee
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Type: text/plain; charset=UTF-8
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: Od: Karl karl@www.photo.gallery
2017-06-13 12:35:50 CLIENT -> SERVER: https://sabatek.pl/kontakt/
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: Wiadomość
2017-06-13 12:35:50 CLIENT -> SERVER: test
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: --b1_4a32b8a2c8807c6ffda0038faf19c5ee
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Type: text/html; charset=UTF-8
2017-06-13 12:35:50 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: <strong>Od:</strong> Karl <a href="/cdn-cgi/l/email-protection#076c66756b476e6a6660627172627f2964686a">karl@www.photo.gallery</a><br>
2017-06-13 12:35:50 CLIENT -> SERVER: https://sabatek.pl/kontakt/<br>
2017-06-13 12:35:50 CLIENT -> SERVER: <br>
2017-06-13 12:35:50 CLIENT -> SERVER: <strong>Wiadomość</strong><br>
2017-06-13 12:35:50 CLIENT -> SERVER: test
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: --b1_4a32b8a2c8807c6ffda0038faf19c5ee--
2017-06-13 12:35:50 CLIENT -> SERVER:
2017-06-13 12:35:50 CLIENT -> SERVER: .
2017-06-13 12:35:50 SERVER -> CLIENT: 250 OK id=1dKl30-000QK2-8K
2017-06-13 12:35:50 CLIENT -> SERVER: QUIT
2017-06-13 12:35:50 SERVER -> CLIENT: 221 s58.hekko.net.pl closing connection
2017-06-13 12:35:50 Connection: closed
true<script>/* <![CDATA[ */(function(d,s,a,i,j,r,l,m,t){try{l=d.getElementsByTagName('a');t=d.createElement('textarea');for(i=0;l.length-i;i++){try{a=l[i].href;s=a.indexOf('/cdn-cgi/l/email-protection');m=a.length;if(a&&s>-1&&m>28){j=28+s;s='';if(j<m){r='0x'+a.substr(j,2)|0;for(j+=2;j<m&&a.charAt(j)!='X';j+=2)s+='%'+('0'+('0x'+a.substr(j,2)^r).toString(16)).slice(-2);j++;s=decodeURIComponent(s)+a.substr(j,m-j)}t.innerHTML=s.replace(/</g,'<').replace(/\>/g,'>');l[i].href='mailto:'+t.value}}catch(e){}}}catch(e){}})(document);/* ]]> */</script>