[exim] 45.10 Outgoing batched SMTP (4.69)

Hello all,

Is this something that aol and optonline would take?

We have a mailing list at the school here that sends mails to the
teachers, (generated by qmail/ezmlm).

Could we setup outgoing batch smtp and reduce the number of total
connections that we make to them?

They are constantly delaying us as ezmlm turns each recipient into a
single email. I have tried to tweak exim to only allow 5 outbound
emails at a time.. but then it takes forever..

So I was hoping by doing the batched smtp for those domains, we could
then pipeline 15-20 msgs at a time per connection.

So my questions are:

Is that a valid reason for using batched smtp?
Would that work? Assuming the domain takes that many msgs per connection..

Anyone have anything they could share from past practice?

Thanks in advance.