I also need help with this
We switched over to OSTicket from Zoho ... and because of this issue we are having to switch back, at least for eBay.
It seems to be only some replies that eBay is randomly blocking. We never had this problem with Zoho - one of the very few things that Zoho seems to actually do well.
In answer to a couple of posts back, yes eBay still obfuscates user email addresses. But if you reply to the eBay-mangled address it should work. Just that sometimes we get a less than completely helpful message back from eBay saying the message could not be delivered.
Yet another reason to drop eBay completely, but for the mean time we have customers freaking out and giving us negative feedback because we can't respond to them. Very bad.
Any suggestions from the community? Has anyone else encountered this problem and found a solution? Super appreciated if you do!