Mailbox as forward and autoresponder
Forward all incoming emails to another address and send responses to senders.
Activate Catch All on Mailbox
Catch-All: if it's on, any email messages sent to a nonexistent account on your domain will go to this address.
Example: your mailbox mailto:email@example.com firstname.lastname@example.org marked as a catch-all. If someone sends an email to <amailto:email@example.com, firstname.lastname@example.org, which doesn't exist, this particular message will arrive at webmaster@1800ssl. If no account were marked as a catch all, this message would bounce back to the sender with an error notification.
Any other mailbox Discard All option.
Turn this Discard all incoming mail ON only if you are sure you don't need ALL your incoming mail. You can also turn it on when you are going on vacation. Senders won't receive 'undelivered mail' notices.