What are your settings for Safe_ports and SSL_ports?
I am using default settings.
acl SSL_ports port 443 563
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 563 # https, snews
acl Safe_ports port 70 # gopher
acl Safe_ports port 210 # wais
acl Safe_ports port 1025-65535 # unregistered ports
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
It seems that I have fixed the problem.
There was something wrong with my squid.conf.
I started applying directives to our environment using a diff file based on
previous config file.
I think the following directives caused the problem but I did not test it
yet.
It was enabled.
acl buggy_server url_regex ^http://....
broken_posts allow buggy_server
I'll give it a try using squid as a transparent proxy as well with these
webmail systems.
Zoltan