Actually WHMCS has a built-in configuration setting for the epp code requirement on per-TLD base which is working fine and except of the entry point for transfers, working and behaving as it should be.
Improvement / Bug:
The initial mask is always showing the epp code input field and is not getting dynamically hidden after domain name input.
Mouse-Over is always pointing out the field being a requirement.
At HEXONET and RRPproxy, there are two different types of Transfers:
* Registrar A to Registrar B
* System-internal Transfer (Customer A to Customer B)
Initiating Inter-Registrar Transfers works well in WHMCS, where initiating system-internal Transfers (in the HEXONET or RRPproxy system) from customer A to customer B isn't a good experience at all for TLDs that do not require an EPP code for transfers (inter-registrar transfer). If configured correctly in WHMCS, no epp code input field will be shown up, but for a customer-to-customer transfer this is mandatory.
TLD examples are: .DK, .AT, ...
Idea: Having a hook at hand that allows to dynamically getting invoked per domain - so after submission of the initial form - and allowing for overwriting the global setting. That would be the best way to achieve a smooth user experience without leading to support cases for resellers and registrars.
Thanks so much!