You can send invitation using custom from e-mail in the invitation e-mail for specific sender domain.
IMPORTANT: You must setup SMTP settings in your Conference Proxy in order to test custom from e-mail for sender domain. If you don't already setup it, please check here.
Step 1
In General settings under Configuration set setting Custom e-mail from for sender domains to "islonline.com=custom-from-domain@islonline.com".
Step 2
Create new meeting and send invitation. If you don't know how to do that, please check here from step 3 to step 6.
Step 3
When you send invitation, "Reply-to" e-mail is actually the e-mail of the host. Since this emails domain is "islonline.com", "From" e-mail is the one you set in Custom e-mail from for sender domains in General settings ("custom-from-domain@islonline.com").