Reply-to SHOULD NOT be considered as from
In v5.3.11, the following was included:
Case #4518 - Use reply-to address from incoming emails when present
This feature should be optional rather than mandatory. Many users configured their WHMCS to allow submitting ticket from registered email address. It is possible that sender has set reply-to address in their email client for other purpose. In such event, reply-to address may not be registered in the system.
So this feature should be added as an option so that we can enable/disable this option as per our need.
I would be great if this can be implemented immediately.