Sending mail, both replies and new messages, is available only if you have an account and are logged in. It takes a few seconds to create an account.
You cannot send as an owned address
If somebody owns an email address, you will not be able to send mail as that address. Thus, to prevent other people from sending messages as your favorite address, you can make that address private.
Sending from a custom domain
First verify ownership of your domain to send from your custom domain.
Sent messages are not saved
Outgoing messages are not saved. They may be visible or cached temporarily by our outgoing mail services, but are not explicitly archived by Mailsac.