Thank you for your reply Falko,
This is weird, in the past I did not have that many problems with emails accounts and websites as today, should I need to upgrade or build a new box?
I've looked on ISPConfig on DNS Manager and select mentioned domain and looked over records and I got:
184.108.40.206 ________ (Priority 10) was alrady there
acui.org.co ________ (Priority 20) I just add it
All my websites on my ISPConfig box are alike, what this was happening before?
What will be the proper settings that should be placed on DNS Manager?