Rails 3.0.17 sending inline attachments instead of regular ones - ruby-on-rails

Question

So, we have just upgraded our project to Rails 3.0.17 (please don't ask why this particular version, just happened so) on top of Ruby 1.8.7 enterprise edition.
I have methods to generate CSV data and send it as a file via email.
# contact_mailer.rb
def send_payments_report
attachments["report.csv"] = {
:content => Payment.generate_csv_report,
:mime_type => "text/csv"
}
mail(
:from => "from#example.com",
:subject => "Payments report",
:to => "to#example.com"
)
end
Here's what it returns:
=> #<Mail::Message:2231891440, Multipart: true, Headers: <Date: Wed, 19 Dec 2012 11:48:05 +0200>, <From: from#example.com>, <To: to#example.com>, <Message-ID: <50d18d555dcdc_2269838ab93812784#artem.local.mail>>, <Subject: Payments report>, <Mime-Version: 1.0>, <Content-Type: multipart/mixed; >, <Content-Transfer-Encoding: 7bit>>
The email itself is displayed as plain text without attachments:
--
Date: Wed, 19 Dec 2012 11:48:05 +0200
Mime-Version: 1.0
Content-Type: text/csv;
charset=UTF-8
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename=report.csv
Content-ID: <50d18d555dcdc_2269838ab93812784#artem.local.mail>
"customer id","reference nr","invoice id","invoice type","invoice sum","sum paid","payment date"
"1035","010294","7113","Fine","250.00","100.00","2012-11-15"
"1035","010294","6132","Fine","250.00","250.00","2012-11-15"
"1035","010294","5241","Fine","850.00","650.00","2012-11-15"
--
I tried attaching existing file, but it displays it the same way. It worked perfectly on Rails 2.3.9. Can anyone help on that?

Answer 1

I seem to have solved this problem.
Here how I call the mail method:
mail(
:from => "from#example.com",
:subject => "Payments report",
:to => "to#example.com"
) do |format|
format.text {render :text => ""}
end