Can Qmail be configured to send a number of emails all at once?

For example -

Cronjobs would send about 10,000 emails to the 10,000 people subscribed to 4 of our websites we are managing.

Then qmail queues mostly all the messages before sending it, When it is in the process of queueing it is already sending some of the messages, but more messages are being qued than being send.

Is there anyway that i can configure qmail to send 100 emails each time it tries to send?

- Current Qmail Settings -

concurrencylocal 10
concurrencyremote 255
queuelifetime 60480 (7 days)
timeoutconnect 60 seconds
timeoutremote 1200 seconds
timeoutsmtpd 1200 seconds

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I use postfix on the other server with the same scenario of sending 10,000 emails a day.

We are migrating the mailing cronjobs to the other server using qmail.

Because when i googled which MTA is faster, most of the results says Qmail is much faster than Postfix.

But when we tested the qmail to handle the 10,000 emails, Qmail queued the messages longer time before sending it compared to Postfix.

Postfix sending of queued messages is much faster than qmail sending of queued messages.

Or I need to tweak the configuration of qmail to send the messages faster?

Thanks in advance.

Additional INFO:

Messages we are sending are not SPAM.

They are notification messages to our customers who are subscribed too 4 of our web sites that we are managing. One of the website is Nationalvisas.com.au