[rt-users] how to check if can receive email from special domain

[nectar]

Sir,

Our RT can not receive email from special domain(for example,
tom at test.com), it is okay before.

a. We can sent email to tom at test.com via RT web UI(create ticket for him)
b. But RT can not receive email from tom at test.com or he can not update ticket
c. If we use my at gmail.com sent email to tom at test.com, my at gmail.com can
get reply email from tom at test.com

If our RT blocked emails from tom at test.com?

Thank you.

--
LiuJia