In creating a new email account today I found that limits were exceeded and that it would not create the account. This must be related to the issue that I have been experiencing with mail being blocked etc. since it appears to be quota related. I dilligently went through all of my domains and email account to lean things out and the system appears to be working as per normal once again.
In short it appears that either ISPCONFIG, quota or the interaction between the 2 are not smart enough to warn before problems like this occur. This is only a guess and I am not trying to start a fueled debate with such a statement that ISPCONFIG is not "smart enough". I love ISPCONFIG and it is a GOD sent in general. I am only mentioning that there may be a problem with quota interaction to hopefully improve development of the next version in the case that there may actually be something here that developers need to address.