My ERC Mail Redirect poped up with strange messages. After weeks of debugging, I believe it is due to the freepops yahoo mail access. I think the latest yahoo.lua should solve the problem.
While debugging, I had tried popmonger and Helexis's Mail Redirect. With Popmonger, I am having the problem that HTML messages are not displayed correctly on Gmail after redirection. Helexis is the best solution so far.