Whenever we try to send an email we receive the message "Outgoing email from "ourdomain.pt" has been suspended..". I have already checked the configuration of the accounts and they are all unrestricted. How do i solve this problem?
You might want to take this up with whoever hosts your website.
Some hosts like GoDaddy etc place limits on how many emails per hour you may send.
Or how many failures per hour.
I'm going to guess that this is where the problem is.