sieve-dev filtering according to attachment type

[Richard Reina]

I am trying to write a recipe that rejects emails that has attachments that
are not either pdf or tiff.  I found this

if header :contains "x-attached"
  [".exe",".bat",".js",".com",".cmd",".ini",".dll",".bas",".cpl",".drv",".inf",".sys",".pif"]
{
  discard;
  stop;
}

in this tutorial http://wiki.fastmail.fm/index.php?title=SieveRecipes


So I tried:

if header :contains "x-attached"
 [".tiff",".pdf"] {
 fileinto "INBOX";
 stop;
} else {
 reject "Your message was returned because of the attachment type. Only pdf
and tiff format allowed";
}

However, it does not work.  The emails get rejected regardless of their
attachment type. That is, emails with pdfs and

tiffs attached get rejected.  What am I doing wrong?  Any help would be
greatly appreciated.

Thanks,

Richard
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