My domains are used for inbound mail only. Replies will be sent from a completely different eMail account. Once, there was a funny guy who sent an eMail from an account that refused any eMail not on the whitelist. In such a case, you will not be able to receive my reply, and I will get very angry for wasting the time typing the reply.
To prevent the harvesting of eMail addresses, all eMail addresses have to be displayed by clicking the name in the footer.