Mailman server crashes on POP3 authentication failure in Rails

Question

I am having a problem - mailman crashes each time after POP3 authentication failure occurs. I have an exception catcher as below but this appear doesn't work:

Mailman::Application.run do
    default do
        begin
          **Some code here**
        rescue Exception => e
          **Calling logger method**
        end
    end
end 

However mailman fails almost every day on this error and dies:

ERROR -- : -ERR [SYS/TEMP] Temporary system problem. Please try again later. (Net::POPAuthenticationError)

I am using Gmail's POP3 and I am sure that server has internet access (using AWS) and I a have monitor which checks if server online every 5 minutes. But even if it goes offline, is it possible to keep mailman checking for e-mails even if POP3 auth fails?