Do you want Haproxy to handle SSL and connect to the backend in cleartext (no SSL)?
Then you need to use the ssl keyword on the frontend, and a cleartext destination port on the backend.
Please check the following 4 changes:
**frontend** webForward <-- this is a frontend section, not a listen section
bind :443 ssl crt /etc/ssl/private/certprivkey.pem no-sslv3
#mode tcp
reqadd X-Forwarded-Proto:\ https
default_backend www-backend
backend www-backend
redirect scheme https if !{ ssl_fc }
#mode tcp
balance roundrobin
stick-table type ip size 200k expire 30m
stick on src
server s1 6x.xxx.xx.xxx:**80** <--- cleartext port 80 here
listen dovecot-imap
bind :993 **ssl crt /etc/ssl/private/certprivkey.pem no-sslv3** <-- specify the ssl keyword, along with certificate configuration here
mode tcp
#option ssl-hello-chk
option http-keep-alive
balance first
tcp-check connect port 993
tcp-check expect string *\ OK
stick-table type ip size 200k expire 15m
stick on src
timeout server 1m
timeout connect 1m
timeout client 5m
server s1 10.0.0.1:**143** send-proxy-v2 <-- should be a cleartext port!
server s2 10.0.0.2:**143** send-proxy-v2 <-- should be a cleartext port!