Log with reason an email account is suspended?

Hi All. I have a Centos VM which is webserver and mailserver for a client. The webserver runs wordpress websites, one of which uses Mailpoet to send newsletters to approx 34,000 subscribers. This uses the local smtp server to send through, login in much as a mail client would. It sends at a rate of 10 emails per minute. The emails are being sent and being received, the list was probably dirty data as we're 50% through sending and receiving over 1000 bounce backs. The email account keeps getting suspended in cpanel. I go in and reactivate and it keeps going. I suspect it could be the amount of deferred and or bounced mail that suspends the account. Going through all sending limits for accounts, domains or email accounts are all unlimited. Is there a log file to get the definitive answer why an email account was suspended from sending? Thanks in advance for any help.