[Mimedefang] Like action_replace_with_url(), but not quite

[Philip Prindeville]

I have a gateway that handles attachments that only make sense for registered users who have the appropriate plugin.

If we detect a user that's not registered is a recipient (possibly one of several), then we need to customize a message just for that user with the attachment stripped and replaced instead with a message saying, "Visit this URL to install the plug-in, register, and pick up your attachment."

We want something like action_replace_with_url() but not quite.

First, the putting the attachment into a lookaside server we'll handle ourselves (or rather, it's already handled).

So I just need to generate the URL, format a replacement entity, call action_rebuild(), and ensure that this message gets delivered to the one recipient (even if the original @Recipients > 1).

How do I go about most efficiently pulling him out of the group-delivery instance and generate a new unique message just for him?

I can't use stream_by_recipient() because I don't know which attachments need to be removed until I hit filter() and not filter_begin().

Note also that each attachment of the proprietary type would need to be uniquely rewritten, but the end-user still only gets one (per-user unique) message.

An example: message M comes along with recipients r1, r2, and r3.

It also has attachments A, B, and C.

It will get delivered to {r1, r2} as is, but it will also be rewritten as: M(r3) to r3 with attachments A, B, C replaced with new entities A(r3), B(r3), C(r3) which r3 can then individually retrieve.

What's the best way to do this?

Thanks,

-Philip