i think they mean certified bank check- http://en.wikipedia.org/wiki/Certified_check but you probably will get better answer from IB banking dept.
it's not about verifying, deposit initiation is about letting IB know,that you are sending money to them. maybe there 10 Relleniums with IB accounts.how they will know,which one is sending the money?
Correct me if I'm wrong but I believe the OP did an ACH pull initiated from the IB side, not an ACH push initiated from the bank side (otherwise his first post about the money not being withdrawn from his bank yet doesn't make sense)
you probably right. to be honest-i mostly use ACH for withdrawals from IB, not for deposits, i dont remember exactly whole procedure but i would call to IB, unstead of wasting time here,asking for all details about ACH from strangers.