This is another log indicating that server went off. None of this logs unfortunately tell us why:
12/27/11 08:58:17 SMTP-OU 6B9BACEE0C464869989606AA911ACD2E.MAI 800 **.103.163.67 DATE 250 Requested mail action okay, completed 263688 43
12/27/11 08:58:17 SMTP-OU 51967A2AC58D49A5980D8EFAB19C2D02.MAI 648 **.103.147.198 DATE 250 2.0.0 pBR6wDQb031851 Message accepted for delivery 263688 56
12/27/11 08:58:17 SMTP-OU 6B9BACEE0C464869989606AA911ACD2E.MAI 800 **.103.163.67 QUIT QUIT 221 Service closing transmission channel 6 42
12/27/11 08:58:17 SMTP-OU 51967A2AC58D49A5980D8EFAB19C2D02.MAI 648 **.103.147.198 QUIT QUIT 221 2.0.0 vega.*****.*** closing connection 6 45
[12/27/11 11:41:08]****************** LOG FILE STARTED *******************
12/27/11 11:41:09 SMTP-OU 004CFFD0A4B945EAAF33FCC50E678D15.MAI 768 **.25.123.219 CONN 220 hs servers POP. Welcome 0 29
12/27/11 11:41:09 SMTP-OU 004CFFD0A4B945EAAF33FCC50E678D15.MAI 768 **.25.123.219 EHLO EHLO mail.*******.*** 250-hs-servers1.*** [95.211.33.140], this server offers 4 extensions 23 130
12/27/11 11:41:09 SMTP-OU 008558DA867240E7BD1667C64B1FD88F.MAI 792 **.30.193.12 CONN 220 mx12.****.** ESMTP - HOL MX Service 0 40
12/27/11 11:41:09 SMTP-OU 004CFFD0A4B945EAAF33FCC50E678D15.MAI 768 **.25.123.219 MAIL MAIL FROM:<marketing@*******.gr> SIZE=263675 250 Requested mail action okay, completed 47 43
12/27/11 11:41:09 SMTP-OU 008558DA867240E7BD1667C64B1FD88F.MAI 792 **.30.193.12 EHLO EHLO mail.netlayer.gr 250-mx12.hol.gr 23 101
12/27/11 11:41:09 SMTP-OU 00B756CBBEAD40A68850221B5094B57C.MAI 1104 **.9.43.184 CONN 220 eu14.netcover.net Spam Protection provided by MagicSpam
www.magicspam.com ESMTP 0 85
12/27/11 11:41:09 SMTP-OU 0208DBF5D2454CD5BA98BEC93DD8C06D.MAI 888 **.103.163.67 CONN 220 mail.arkonet.****** SMTP v1.0 0 31
12/27/11 11:41:09 SMTP-OU 00B756CBBEAD40A68850221B5094B57C.MAI 1104 **.9.43.184 EHLO EHLO mail.*****.**** 250-eu14.netcover.net Spam Protection provided by MagicSpam
www.magicspam.com 23 185
12/27/11 11:41:09 SMTP-OU 00B756CBBEAD40A68850221B5094B57C.MAI 1104 **.9.43.184 MAIL MAIL FROM:<marketing@*******.gr> 250 ok 35 8