Default drop rule

Hello,

I have a problem with this rule.
When I make a "aptitude install my packet", for some packets, I have a time out.

By analyzing the logs of the firewall, I am perceived that I had errors, in particular "Default Drop" since the serveur security.debian.org:eek:.

Does anybody know not how to have more this error because impossible to install my mail server?

I'm sorry for my english but it's little bad.

Thank you for your reponses.

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