IMAP fetch ignores ssl switch
In lib/redmine/imap.rb the line
ssl = !imap_options[:ssl].nil?
sets ssl to true whenever imap_options[:ssl] has any value.
So, if we call rake task redmine:email:receive_imap with argument "ssl=false" oder "ssl=0" or whatever, SSL is used anyway. The only way to disable SSL is to omit the "ssl=" argument, which is not very convenient if the command line for the task is generated by a script.