Hi,
First thing to check is if these emails are stuck in your queue.
Second thing you can check is your cron report. You'll find it in Acymailimg->Configuration->Queue process under the Advanced section,. It might reveal details about why the sendig stopped.
In case cron reports are disabled, please change the report to be saved eacht time Acymailing performs an action.
If you can't find out what happened, just send the campaign a second time. On the summary tab Acymailing will ask you if it has to send the email to all users (including the ones that already received the email) or to send it only to new subscribers that did not receive the email already.
Afterwards check the log file to see what happened.
