Only items handled by the ACH network will be reflected in the calculation of an Originator's returns percentage. A percentage of 0.5% or greater will attract attention from NACHA and could result in a penalty or getting locked out of the network.
If your eChecks are computer-originated images designed to appear as remotely created checks (sometimes called consumer drafts), it's my understanding those images are cleared via the check clearing networks, not through the ACH network.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8