$attachments->Limit ( FIELD => 'ContentType', OPERATOR => '=', VALUE => 'text/plain');
$attachments->Limit ( FIELD => 'ContentType', OPERATOR => 'STARTSWITH', VALUE => 'message/');
$attachments->Limit ( FIELD => 'ContentType', OPERATOR => '=', VALUE => 'text');
$attachments->Limit ( FIELD => 'ContentType', OPERATOR => '=', VALUE => 'text/plain');
$attachments->Limit ( FIELD => 'ContentType', OPERATOR => 'STARTSWITH', VALUE => 'message/');
$attachments->Limit ( FIELD => 'ContentType', OPERATOR => '=', VALUE => 'text');