sorry for the delay, i was out of the office yesterday. i have some connection attempt log on the IMAP exchange log dateTime,sessionId,seqNumber,sIp,cIp,user,duration,rqsize,rpsize,command,parameters,context#Software: Microsoft Exchange Server#Version: 15.0.0.0#Log-type: IMAP4 Log#Date: 2018-02-14T14.097Z#Fields: dateTime,sessionId,seqNumber,sIp,cIp,user,duration,rqsize,rpsize,command,parameters,context2018-02-14T14.097Z,0000000000000001,0,192.168.5.26,192.168.5.210,,223,0,53,OpenSession,,2018-02-14T14.331Z,0000000000000001,1,192.168.5.26,192.168.5.210,,98,19,147,capability,,R=ok2018-02-14T14.441Z,0000000000000001,2,192.168.5.26,192.168.5.210,,22,39,71,authenticate,GSSAPI,"R=""00000001 NO The AUTH protocol exchange was canceled by the client."";Msg=AuthCancelled"2018-02-14T14.066Z,0000000000000002,0,127.0.0.1,127.0.0.1,,43,0,53,OpenSession,,2018-02-14T14.066Z,0000000000000002,1,127.0.0.1,127.0.0.1,,1,12,140,capability,,R=ok2018-02-14T14.081Z,0000000000000002,2,127.0.0.1,127.0.0.1,,0,0,0,CloseSession,,2018-02-14T14.566Z,0000000000000001,3,192.168.5.26,192.168.5.210,osticket,3111,38,37,authenticate,PLAIN,"R=""00000002 NO AUTHENTICATE failed."";Msg=Proxy:************;ErrMsg=ProxyFailed;LiveIdAR=OK;Excpt=""Aucune connexion n’a pu être établie car l’ordinateur cible l’a expressément refusée ************-System.Net.Sockets.SocketException"";ExStk=H4sIAAAAAAAEAHVPMU4DMRDskfjDlrnG8gUSJemiU5BSgCLuBY6zAYs7r7VeS76Ob9DRhm/cT3gJDgpCFFQ72pmdmW2HKNirBxTVkn1BiZe5yRaDOPIw0Xmhtb7VelatYJ1s8giWvMd8pv3n65uBkGD8EEYYT2L2nSsKw9AVjvjgvBFMDNbtO/xeGsAcGGMcTz16AcZjKhihXk5VPV+omZrOV/VyeXN9BQDjO7T/FVUbf2jObaxMtus4ePuIMXUC5hdXPy73zjJFOparbJ+Nf0K1o7DtTVANMaoiD+Qj3hkrxIPaMeXh4l6ebagPHQr+DXKGqy/yQ3zISAEAAA=="2018-02-14T14.644Z,0000000000000001,4,192.168.5.26,192.168.5.210,osticket,2075,38,37,authenticate,PLAIN,"R=""00000003 NO AUTHENTICATE failed."";Msg=Proxy:************;ErrMsg=ProxyFailed;LiveIdAR=OK;Excpt=""Aucune connexion n’a pu être établie car l’ordinateur cible l’a expressément refusée ************-System.Net.Sockets.SocketException"";ExStk=H4sIAAAAAAAEAHVPMU4DMRDskfjDlrnG8gUSJemiU5BSgCLuBY6zAYs7r7VeS76Ob9DRhm/cT3gJDgpCFFQ72pmdmW2HKNirBxTVkn1BiZe5yRaDOPIw0Xmhtb7VelatYJ1s8giWvMd8pv3n65uBkGD8EEYYT2L2nSsKw9AVjvjgvBFMDNbtO/xeGsAcGGMcTz16AcZjKhihXk5VPV+omZrOV/VyeXN9BQDjO7T/FVUbf2jObaxMtus4ePuIMXUC5hdXPy73zjJFOparbJ+Nf0K1o7DtTVANMaoiD+Qj3hkrxIPaMeXh4l6ebagPHQr+DXKGqy/yQ3zISAEAAA=="2018-02-14T14.722Z,0000000000000001,5,192.168.5.26,192.168.5.210,osticket,2078,38,69,authenticate,PLAIN,"R=""00000004 NO AUTHENTICATE failed.\r\n* BYE Connection is closed. 14"";Msg=Proxy:************;ErrMsg=ProxyFailed;LiveIdAR=OK;Excpt=""Aucune connexion n’a pu être établie car l’ordinateur cible l’a expressément refusée 192.168.5.26-System.Net.Sockets.SocketException"";ExStk=H4sIAAAAAAAEAHVPMU4DMRDskfjDlrnG8gUSJemiU5BSgCLuBY6zAYs7r7VeS76Ob9DRhm/cT3gJDgpCFFQ72pmdmW2HKNirBxTVkn1BiZe5yRaDOPIw0Xmhtb7VelatYJ1s8giWvMd8pv3n65uBkGD8EEYYT2L2nSsKw9AVjvjgvBFMDNbtO/xeGsAcGGMcTz16AcZjKhihXk5VPV+omZrOV/VyeXN9BQDjO7T/FVUbf2jObaxMtus4ePuIMXUC5hdXPy73zjJFOparbJ+Nf0K1o7DtTVANMaoiD+Qj3hkrxIPaMeXh4l6ebagPHQr+DXKGqy/yQ3zISAEAAA=="sorry for the small part in french, it's mean connection refused because target computer refused itwhat bother me is that it's say: ,authenticate,PLAIN. even if the setting is set to IMAP+SSL on port 993i have try to connect with IMAP only on port 143 and the same log appear on the logfile with only the port number that is different.