This ticket amends ticket 0002361, which was closed without resolving the issue.

According to the SOGo Installation Guide and a comment in SOGoUser.m TLS connections to the IMAP server have to be configured with the "imaps" scheme. The documentation and the comment in the source code are wrong.

The code in SOGoUser.m will always use SSL if the "imaps" scheme is given. TLS only works if the "imap" scheme along with "?tls=YES" is used in the configured URI.

Below is the relevant code section from SOGoUser.m, which shows that "encryption" will only be set to "tls" if the "imaps" scheme is NOT given:

if (scheme
&& [scheme caseInsensitiveCompare: @"imaps"] == NSOrderedSame)
{
encryption = @"ssl";
defaultPort = 993;
}
else
{
query = [cUrl query] ? [cUrl query] : [url query];
if (query && [query caseInsensitiveCompare: @"tls=YES"] == NSOrderedSame)
encryption = @"tls";
else
encryption = @"none";
defaultPort = 143;
}