You can configure most email clients and webmails to use a custom sending address. This is how it's done for mailbox.my: https://www.mailbox.my/setup_clients.h

You can configure most email clients and webmails to use a custom sending address. This is how it's done for mailbox.my: https://www.mailbox.my/setup_clients.html https://www.mailbox.my/setup_clients.html (Disclosure: My project)