Apparently they are investigating a DDoS that's affecting everything including their API, email sending, etc...
You can keep track of things on this page: GetResponse Status
UPDATE: This thread was originally started within 30 minutes after the DDoS attack started. It's been over 72 hours. Click Here To Read The GetResponse CEO Statement Regarding the DDoS Attack
From what I've seen, it's going to be a couple more days until service is fully restored.
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MickK (GetResponse Affiliate Manager) Warrior Forum Thread On GetResponse Attack