With perl 5.10.1 Mail::IMAPClient  3.38
Command line used:
/usr/bin/imapsync --host1 zcs-proxy01 --port1 993 --ssl1 --user1 EMAIL --password1 MASKED --host2 imap.gmail.com --ssl2 --user2 EMAIL --password2 MASKED --justfoldersizes --nofoldersizes --authmech2 XOAUTH2 --debug
Temp directory is /tmp  ( to change it use --tmpdir dirpath )
PID file is /tmp/imapsync.pid ( to change it use --pidfile filepath ; to avoid it use --pidfile "" )
Modules version list:
Mail::IMAPClient     3.38
IO::Socket           1.31
IO::Socket::IP       0.37
IO::Socket::INET     1.31
IO::Socket::SSL      1.31
Net::SSLeay          1.35
Compress::Zlib       2.069
Digest::MD5          2.39
Digest::HMAC_MD5     1.01
Digest::HMAC_SHA1    1.01
Term::ReadKey        2.30
File::Spec           3.3
Time::HiRes          1.9721
Unicode::String      2.09
IO::Tee              0.64
File::Copy::Recursive 0.38
Authen::NTLM         1.09
URI::Escape          3.29
Data::Uniqid         0.12
JSON                 2.90
JSON::WebToken       0.10
Crypt::OpenSSL::RSA  0.28
LWP                  6.15
HTML::Entities       3.69
Filesys::DfPortable  0.85
( use --no-modules_version to turn off printing this Perl modules list )
Use --sslargs1 SSL_verify_mode=1 for SSL_VERIFY_PEER on host1
Use --sslargs2 SSL_verify_mode=1 for SSL_VERIFY_PEER on host2
ssl debug mode level is --debugssl 1 (can be set from 0 meaning no debug to 4 meaning max debug)
IMAPClient 3.38
Info: turned ON syncinternaldates, will set the internal dates (arrival dates) on host2 same as host1.
Host1: will try to use LOGIN authentication on host1
Host2: will try to use XOAUTH2 authentication on host2
Host1: imap connexion timeout is 120 seconds
Host2: imap connexion timeout is 120 seconds
Host1: IMAP server [zcs-proxy01] port [993] user [EMAIL]
Host2: IMAP server [imap.gmail.com] port [993] user [EMAIL]
Host1: connecting and login on host1 [zcs-proxy01] port [993] with user [EMAIL]
Use of uninitialized value $sockargs[9] in join or string at /usr/local/share/perl5/Mail/IMAPClient.pm line 360.
Host1 banner: * OK IMAP4 ready
Host1: zcs-proxy01 says it has NO CAPABILITY for AUTHENTICATE LOGIN
Host1: success login on [zcs-proxy01] with user [EMAIL] auth [LOGIN]
Host2: connecting and login on host2 [imap.gmail.com] port [993] with user [EMAIL]
Use of uninitialized value $sockargs[9] in join or string at /usr/local/share/perl5/Mail/IMAPClient.pm line 360.
Host2 failure: can not open imap connection on host2 [imap.gmail.com] with user [EMAIL]: Unable to connect to imap.gmail.com: