utl_mail adds CRLF at beginning of varchar2 attachments

Using 10.2.0.3.0 on solaris, I'm trying to write some tests against utl_mail.send_attach_varchar2. I receive the email and the attachments, but the attachment always begins with a leading blank line. I've tried varying the att_mime_type but am still having the same problem. The leading blank line is preventing applications from interpreting my RTF text.

Here's the code I'm using. This example uses RTF, but examples using straight text have also failed (below)

rtf example:
exec UTL_MAIL.SEND_ATTACH_VARCHAR2(

         sender => 'xxx_at_domain.com'
        ,recipients => 'xxx_at_domain.com'
        ,cc => NULL
        ,bcc =>  NULL
        ,subject => 'send_attach_varchar2'
        ,message => 'here is a test of send_attach_varchar2'
        ,mime_type => 'text/plain; charset=us-ascii'
        ,priority => 3
        ,attachment => '{\rtf1\ansi{\fonttbl\f0\fswiss Helvetica;}
\f0\pard This is some {\b bold} text.\par}'
        ,att_inline => TRUE
        ,att_mime_type=>'application/rtf'
        ,att_filename => 'rtftest2.rtf'

plain text example:
exec UTL_MAIL.SEND_ATTACH_VARCHAR2(
sender => 'xxx_at_oracle.com'
,recipients => 'xxx_at_domain.com'
,cc => NULL
,bcc => NULL
,subject => 'scheduled disco mail'
,message => 'Testing testing testing'
,mime_type => 'text/plain; charset=us-ascii'
,priority => 1
,attachment => 'should be in my attachment'
,att_inline => FALSE
,att_mime_type => 'text/plain; charset=us-ascii'
,att_filename => 'neil.txt'

); Received on Tue May 06 2008 - 14:00:25 CDT