Hello, Firstly I would like to thank anyone how can tell me how to correct this issue. I have installed ISPC3 on Debian 7, in a multi-server set up, with dedicated Mail, Database, Web, NS. The Others are working fine, but the emails aren't being processed properly, I have set up the router so that it correctly forwards the emails and they are being received by the Email Server(s) but aren't being processed and inserted into the inboxes and all emails are bouncing back. The mail Queue looks like this, (EMAIL ADDRESS'S HAVE BEEN CHANGED FOR PRIVACY). Mail Queue (Server : Email Server) Data from: 2014-07-15 16:35 -Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient------- 8EFAC430F2 759 Mon Jul 14 15:18:03 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02176-03 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 108.): id=02176-03 (in reply to end of DATA command)) [email protected] 1837B43132 688 Tue Jul 15 15:43:03 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02175-04 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 135.): id=02175-04 (in reply to end of DATA command)) [email protected] 1DB0343106 695 Mon Jul 14 16:10:02 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02175-01 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 27.): id=02175-01 (in reply to end of DATA command)) test3.Domain.com 44A77430AF 691 Sat Jul 12 15:00:19 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02176-01 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 27.): id=02176-01 (in reply to end of DATA command)) [email protected] 09380430D1 687 Mon Jul 14 16:00:08 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02176-02 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 54.): id=02176-02 (in reply to end of DATA command)) [email protected] 6BE5043116 687 Mon Jul 14 15:47:01 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02175-02 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 54.): id=02175-02 (in reply to end of DATA command)) [email protected] 2B03C430CE 695 Sat Jul 12 15:00:18 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=02175-02-2 - Temporary MTA failure on relaying, From MTA() during fwd-connect (Negative greeting: at (eval 109) line 479, line 81.): id=02175-02-2 (in reply to end of DATA command)) [email protected] -- 7 Kbytes in 7 Requests. If you need anything else, please just ask.