ActionMailer/url_for issue

I keep running into this one:

Immediately after EventMailer.deliver_whatever, url_for doesn’t work
with the usual parameters, e.g.,

url_for(:controller => ‘monkeys’, :action => ‘fly’, :something =>
“some_parameter”)

I consistently get an exception, with the message:

undefined method `rewrite’ for #String:0x277e9f4

The rest of the stack trace shows that the exception is indeed being
generated by url_for

All of this works fine if I call it before EventMailer.deliver_blah.

Does anybody have an idea what might be happening?

Thanks,

–Al Evans