Hi I'm using the latest Stunnel (5.35), running under Windows Server 2000, to download emails from Outlook(Office365)/Outlook 2016 to another email client called OfficeTalk which only supports unencrypted POP3, so it can't access Outlook directly. First problem is that although most emails are downloaded without problem, some stubbornly and consistently refuse to be downloaded. This omission doesn't seem related to attachments, encoding, size, date, or anything else that I can see. Has anyone else experienced this or have any idea why it might be happening?? Second problem is that the first download doesn't produce anything, but if I run the request again, it works - the only difference in the log files is the IP addresses I'd greatly appreciate any advice on this - I've checked the threads but can't find anything similar. Many thanks in advance Martin

Config file for all attempts is:debug=7 output = c:\program files\stunnel\stunnel.log [outlook-pop3] client = yes accept = 127.0.0.1:110 connect = outlook.office365.com:995 Logfile for successful download of one email is:12:49:50 LOG7[cron]: Cronthread initialized12:49:50 LOG7[main]: Runningon Windows 5.012:49:50 LOG7[main]: No limitdetected for the number of clients12:49:50 LOG5[main]: stunnel5.35 on x86-pc-msvc-1500 platform12:49:50 LOG5[main]:Compiled/running with OpenSSL 1.0.2h-fips 3 May 201612:49:50 LOG5[main]:Threading:WIN32 Sockets:SELECT,IPv4 TLS:ENGINE,FIPS,OCSP,PSK,SNI12:49:50 LOG7[main]: errno:(*_errno())12:49:50 LOG7[ui]: GUImessage loop initialized12:49:50 LOG7[main]: Runningon Windows 5.012:49:50 LOG5[main]: Reading configurationfrom file stunnel.conf12:49:50 LOG5[main]: UTF-8byte order mark detected12:49:50 LOG5[main]: FIPSmode disabled12:49:50 LOG7[main]:Compression disabled12:49:50 LOG7[main]: Snagged64 random bytes from C:/.rnd12:49:50 LOG7[main]: Wrote1024 new random bytes to C:/.rnd12:49:50 LOG7[main]: PRNGseeded successfully12:49:50 LOG6[main]:Initializing service [outlook-pop3]12:49:50 LOG7[main]: Nocertificate or private key specified12:49:50 LOG4[main]: Service[outlook-pop3] needs authentication to prevent MITM attacks12:49:50 LOG7[main]: SSLoptions: 0x03000004 (+0x03000000, -0x00000000)12:49:50 LOG5[main]:Configuration successful12:49:50 LOG7[main]:Listening file descriptor created (FD=344)12:49:50 LOG7[main]: Service[outlook-pop3] (FD=344) bound to 127.0.0.1:11012:49:53 LOG7[main]: Found 1ready file descriptor(s)12:49:53 LOG7[main]: FD=204ifds=r-x ofds=---12:49:53 LOG7[main]: Service[outlook-pop3] accepted (FD=356) from 127.0.0.1:380112:49:53 LOG7[main]: Creatinga new thread12:49:53 LOG7[main]: Newthread created12:49:53 LOG7[0]: Service[outlook-pop3] started12:49:53 LOG7[0]: OptionTCP_NODELAY set on local socket12:49:53 LOG5[0]: Service[outlook-pop3] accepted connection from 127.0.0.1:380112:49:53 LOG6[0]: failover:round-robin, starting at entry #112:49:53 LOG6[0]: s_connect:connecting 132.245.224.162:99512:49:53 LOG7[0]: s_connect:s_poll_wait 132.245.224.162:995: waiting 10 seconds12:49:53 LOG5[0]: s_connect:connected 132.245.224.162:99512:49:53 LOG5[0]: Service[outlook-pop3] connected remote server from 192.168.15.102:380212:49:53 LOG7[0]: OptionTCP_NODELAY set on remote socket12:49:53 LOG7[0]: Remotedescriptor (FD=380) initialized12:49:53 LOG6[0]: SNI:sending servername: outlook.office365.com12:49:53 LOG6[0]: Peercertificate not required12:49:53 LOG7[0]: SSL state(connect): before/connect initialization12:49:53 LOG7[0]: SSL state(connect): SSLv2/v3 write client hello A12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server hello A12:49:53 LOG6[0]: Certificateverification disabled12:49:53 LOG6[0]: Certificateverification disabled12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server certificate A12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server key exchange A12:49:53 LOG6[0]: Clientcertificate not requested12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server done A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write client key exchange A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write change cipher spec A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write finished A12:49:53 LOG7[0]: SSL state(connect): SSLv3 flush data12:49:53 LOG7[0]: SSL state(connect): SSLv3 read finished A12:49:53 LOG7[0]:      1 client connect(s) requested12:49:53 LOG7[0]:      1 client connect(s) succeeded12:49:53 LOG7[0]:      0 client renegotiation(s) requested12:49:53 LOG7[0]:      0 session reuse(s)12:49:53 LOG6[0]: SSLconnected: new session negotiated12:49:53 LOG7[0]: Peercertificate was cached (4882 bytes)12:49:53 LOG6[0]: NegotiatedTLSv1.2 ciphersuite ECDHE-RSA-AES256-SHA384 (256-bit encryption)12:49:53 LOG7[0]:Compression: null, expansion: null12:49:54 LOG6[0]: Read socketclosed (readsocket)12:49:54 LOG7[0]: Sendingclose_notify alert12:49:54 LOG7[0]: SSL alert(write): warning: close notify12:49:54 LOG6[0]:SSL_shutdown successfully sent close_notify alert12:49:54 LOG7[main]: Found 1ready file descriptor(s)12:49:54 LOG7[main]: FD=204ifds=r-x ofds=---12:49:54 LOG7[main]: Service[outlook-pop3] accepted (FD=404) from 127.0.0.1:380312:49:54 LOG7[main]: Creatinga new thread12:49:54 LOG7[main]: Newthread created12:49:54 LOG7[1]: Service[outlook-pop3] started12:49:54 LOG7[1]: OptionTCP_NODELAY set on local socket12:49:54 LOG5[1]: Service[outlook-pop3] accepted connection from 127.0.0.1:380312:49:54 LOG6[1]: failover:round-robin, starting at entry #212:49:54 LOG6[1]: s_connect:connecting 132.245.212.98:99512:49:54 LOG7[1]: s_connect:s_poll_wait 132.245.212.98:995: waiting 10 seconds12:49:54 LOG6[0]: SSL socketclosed (SSL_read)12:49:54 LOG7[0]: Sent socketwrite shutdown12:49:54 LOG5[0]: Connectionclosed: 67 byte(s) sent to SSL, 11900 byte(s) sent to socket12:49:54 LOG7[0]: Remotedescriptor (FD=380) closed12:49:54 LOG7[0]: Local descriptor(FD=356) closed12:49:54 LOG7[0]: Service[outlook-pop3] finished (1 left)12:49:54 LOG5[1]: s_connect:connected 132.245.212.98:99512:49:54 LOG5[1]: Service[outlook-pop3] connected remote server from 192.168.15.102:380412:49:54 LOG7[1]: OptionTCP_NODELAY set on remote socket12:49:54 LOG7[1]: Remotedescriptor (FD=428) initialized12:49:54 LOG6[1]: SNI:sending servername: outlook.office365.com12:49:54 LOG6[1]: Peercertificate not required12:49:54 LOG7[1]: SSL state(connect): before/connect initialization12:49:54 LOG7[1]: SSL state(connect): SSLv3 write client hello A12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server hello A12:49:54 LOG6[1]: Certificateverification disabled12:49:54 LOG6[1]: Certificateverification disabled12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server certificate A12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server key exchange A12:49:54 LOG6[1]: Clientcertificate not requested12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server done A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write client key exchange A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write change cipher spec A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write finished A12:49:54 LOG7[1]: SSL state(connect): SSLv3 flush data12:49:54 LOG7[1]: SSL state(connect): SSLv3 read finished A12:49:54 LOG7[1]:      2 client connect(s) requested12:49:54 LOG7[1]:      2 client connect(s) succeeded12:49:54 LOG7[1]:      0 client renegotiation(s) requested12:49:54 LOG7[1]:      0 session reuse(s)12:49:54 LOG6[1]: SSLconnected: new session negotiated12:49:54 LOG7[1]:Deallocating application specific data for addr index12:49:54 LOG6[1]: NegotiatedTLSv1.2 ciphersuite ECDHE-RSA-AES256-SHA384 (256-bit encryption)12:49:54 LOG7[1]:Compression: null, expansion: null12:49:56 LOG6[1]: Read socketclosed (readsocket)12:49:56 LOG7[1]: Sendingclose_notify alert12:49:56 LOG7[1]: SSL alert(write): warning: close notify12:49:56 LOG6[1]:SSL_shutdown successfully sent close_notify alert12:49:56 LOG6[1]: SSL socketclosed (SSL_read)12:49:56 LOG7[1]: Sent socketwrite shutdown12:49:56 LOG5[1]: Connectionclosed: 67 byte(s) sent to SSL, 11884 byte(s) sent to socket12:49:56 LOG7[1]: Remotedescriptor (FD=428) closed12:49:56 LOG7[1]: Localdescriptor (FD=404) closed12:49:56 LOG7[1]: Service[outlook-pop3] finished (0 left)