G Suite migration using dsync

[Paul Pace]

Hello,

I am trying to migrate a domain from G Suite using dsync and am not 
clear on how to configure so I am getting failures.

This is the configuration in dovecot.conf:

imapc_host = imap.gmail.com
imapc_port = 993
imapc_password = 1234
imapc_ssl = imaps
imapc_ssl_verify = yes
imapc_features = gmail-migration

I also tried with imapc_ssl_verify commented.

For simplicity, both the username and password are the same for G Suite 
and Dovecot and are verified to access the G Suite account with other tools.

Here is the command (from the wiki) and output:

# doveadm backup -a 'virtual/All' -O '-$GmailHaveLabels' -R -u 
user at example.com imapc:
dsync(user at example.com): Info: imapc(imap.gmail.com:993): Connected to 
2607:f8b0:4003:c0f::6c:993 (local IPv6:port)
dsync(user at example.com): Warning: imapc(imap.gmail.com:993): Server 
disconnected unexpectedly: SSL_connect() failed: error:14094410:SSL 
routines:ssl3_read_bytes:sslv3 alert handshake failure: SSL alert number 
40 - reconnecting (delay 0 ms)
dsync(user at example.com): Info: imapc(imap.gmail.com:993): Connected to 
74.125.30.109:993 (local IPv4:port)
dsync(user at example.com): Error: imapc(imap.gmail.com:993): Server 
disconnected unexpectedly: SSL_connect() failed: error:14094410:SSL 
routines:ssl3_read_bytes:sslv3 alert handshake failure: SSL alert number 
40 - disconnecting
dsync(user at example.com): Error: User initialization failed: imapc: Login 
to imap.gmail.com failed: Disconnected from server

In reading through the wiki, it seems I am missing something, but I 
can't figure out what is missing and internet searches don't provide 
further useful information on the dovecot tools.

Thank you,

Paul