Mail subject is a question mark

Mail subject is a question mark

Hi i have some trouble with my email subject which is typed mostly in Greek language.
When i send an email from my online shop the subject of the message is marked with ????????.
I am attaching a picture and the 'Show original: from Google mail. 

  
    
   
  1. Delivered-To: gxtidus@gmail.com
    2. 
   
  2. Received: by 10.70.53.99 with SMTP id a3csp118464pdp;
    3. 
   
  3.  Thu, 4 Dec 2014 11:16:25 -0800 (PST)
    4. 
   
  4. X-Received: by 10.66.189.100 with SMTP id gh4mr20850275pac.131.1417720585791;
    5. 
   
  5.  Thu, 04 Dec 2014 11:16:25 -0800 (PST)
    6. 
   
  6. Return-Path: <sales@e-exelixi.gr>
    7. 
   
  7. Received: from sender1.zohomail.com (sender1.zohomail.com. [74.201.84.155])
    8. 
   
  8.  by mx.google.com with ESMTPS id wp13si35728915pac.230.2014.12.04.11.16.25
    9. 
   
  9.  for <gxtidus@gmail.com>
    10. 
   
  10.  (version=TLSv1 cipher=RC4-SHA bits=128/128);
    11. 
   
  11.  Thu, 04 Dec 2014 11:16:25 -0800 (PST)
    12. 
   
  12. Received-SPF: softfail (google.com: domain of transitioning sales@e-exelixi.gr does not designate 74.201.84.155 as permitted sender) client-ip=74.201.84.155;
    13. 
   
  13. Authentication-Results: mx.google.com;
    14. 
   
  14.  spf=softfail (google.com: domain of transitioning sales@e-exelixi.gr does not designate 74.201.84.155 as permitted sender) smtp.mail=sales@e-exelixi.gr
    15. 
   
  15. Message-Id: <5480b309.6df2420a.39ee.ffffbd7fSMTPIN_ADDED_MISSING@mx.google.com>
    16. 
   
  16. Received: from e-exelixi.gr (178.62.217.131 [178.62.217.131]) by mx.zohomail.com
    17. 
   
  17.  with SMTPS id 1417720583755879.865167466252; Thu, 4 Dec 2014 11:16:23 -0800 (PST)
    18. 
   
  18. Return-Path: sales@e-exelixi.gr
    19. 
   
  19. MIME-Version: 1.0
    20. 
   
  20. To: gxtidus@gmail.com
    21. 
   
  21. Subject: e-eXelixi.gr ???????????????????????? ?????????????????????? - ???????????????? ?????????????? - ???????????????????? 27
    22. 
   
  22. Date: Thu, 04 Dec 2014 19:16:21 +0000
    23. 
   
  23. From: =?UTF-8?B?ZS1lWGVsaXhpLmdyIM6XzrvOtc66z4TPgc6/zr3Ouc66zr/OryDPhc+Azr/Ou86/zrPOuc+Dz4TOrc+CIC0gzqTOsc68zrnOsc66zq3PgiDOvM63z4fOsc69zq3Pgg==?= <sales@e-exelixi.gr>
    24. 
   
  24. Reply-To: =?UTF-8?B?ZS1lWGVsaXhpLmdyIM6XzrvOtc66z4TPgc6/zr3Ouc66zr/OryDPhc+Azr/Ou86/zrPOuc+Dz4TOrc+CIC0gzqTOsc68zrnOsc66zq3PgiDOvM63z4fOsc69zq3Pgg==?= <sales@e-exelixi.gr>
    25. 
   
  25. X-Mailer: PHP/5.5.18
    26. 
   
  26. Content-Type: multipart/related; boundary="----=_NextPart_f4d1daea9f7903bbf32e6cee477feee8"
    27. 
   
  27. X-ZohoMailClient: External
    28. 
   
  28. X-Zoho-Virus-Status: 2
    29. 
   

    30. 
   
  30. ------=_NextPart_f4d1daea9f7903bbf32e6cee477feee8
    31. 
   
  31. Content-Type: text/plain; charset="utf-8"
    32. 
   
  32. Content-Transfer-Encoding: 8bit
    33. 
   

    34. 
   
  34. ΞˆΟ‡Ξ΅Ο„Ξ΅ λάβΡι ΞΌΞΉΞ± παραγγΡλία.
    35. 
   

    36. 
   
  36. Ξ‘ΟΞΉΞΈΞΌΟŒΟ‚ ΠαραγγΡλίας: 27
    37. 
   
  37. ΗμΡρομηνία ΞšΞ±Ο„Ξ±Ο‡ΟŽΟΞ·ΟƒΞ·Ο‚: 04/12/2014
    38. 
   
  38. ΞšΞ±Ο„Ξ¬ΟƒΟ„Ξ±ΟƒΞ· ΠαραγγΡλίας: ΕκκρΡμΡί
    39. 
   

    40. 
   
  40. Ξ ΟΞΏΟŠΟŒΞ½Ο„Ξ±
    41. 
   
  41. 1x 621001 C-200 (621001 C-200) 3,38€
    42. 
   

    43. 
   
  43. Σύνολα ΠαραγγΡλίας
    44. 
   
  44. ΜΡρικό Σύνολο: 2,75€
    45. 
   
  45. ΧΡρσαίοι Προορισμοί (Βάρος: 0.31kg): 4,30€
    46. 
   
  46. ΞšΟŒΟƒΟ„ΞΏΟ‚ αντικαταβολΞ�Ο‚: 2,90€
    47. 
   
  47. ΦΠΑ (23%): 0,63€
    48. 
   
  48. Σύνολο: 10,58€
    49. 
   

    50. 
   

    51. 
   
  51. ------=_NextPart_f4d1daea9f7903bbf32e6cee477feee8--
    52.


Is there any way to fix this? 
Thanks in advance.