I guess an html_p column is to be added to acs_mail_lite_queue
The sweeper code is to become:
db_foreach get_queued_messages {} {
set eh [util_list_to_ns_set $extra_headers]
if {$html_p} { ns_set put $eh Content-Type text/html }
if {[catch {ns_sendmail $to_addr $from_addr $subject $body $eh $bcc} errmsg]} {
ns_log Error "ns_sendmail failed: $errmsg"
} else {
db_dml delete_queue_entry {}
}
}