For eligius or any other pool:
1-3% rejects is normal; everything <1% is fake or barely possible, like x8s did: it only rejected outdated shares which made it get <0.5%, for proportional only pools this makes sense in terms of saves trouble on the pools bitcoind side; for PPS it shouldn't accept any invalid outdated stale shares ever as the pool pays for them directly.

For login credentials:
user@domain.com_username2 wont work ever as .com_username2 is no toplevel domain any dns knows about. use proper json formated configs with "-c config.json" or use the commands "-o domain.com:port -u username -p password" and it might work