ActionMailer Caching

Hi everyone

I've a big problem with sending a mail over ActionMailer::Base (HTML
mail). I deploy my app with capistrano (2.5.9) and use passenger
(2.2.15) / apache as webserver. But sometimes, when a send a mail, it
takes an old template (of an old release of capistrano) and encode the
content not to html. The template has the extension ...text.html.haml.
The email receive every customer as followed:

<p>Dear Customer</p>

It's very strange, because the symptom occurs not every time of sending.
Is it possible, that a compontent in the mail sending-chain is caching
an old template and doesn't encode it?

I've no plan whats wrong! Please help me...