[kh99]

In the admicp under Settings > Options > Email Options, if you have Use Mailqueue System and Use Cron Based Sending set to Yes, then you need to make sure "Number of Emails to Send Per Batch" is set high enough. The cron job runs 6 times per hour, so the value should be about 1/6 of the max emails you want to send out per hour.

If you go to the admincp home page, in the right column of info at the top there's a "Number of Queued E-Mails", so you can check that to see if the queue is the problem.