This is a question people often face when setting up their email accounts.
Usually, we will have a few email accounts setup in our domain as email@example.com, firstname.lastname@example.org & email@example.com etc.
Now, what will happen, if someone send an email to firstname.lastname@example.org.
Will it bounce?
It can be configured either to bounce or to silently reject.
Standard and recommended configuration is definitely to bounce emails to non existing email accounts. This will help the sender to know if recipient email account does not exist and he can try again to send to correct email address.
If your domain is a target of spam and you are receiving too many emails to non existing email accounts, you can configure email settings to reject emails to non existing email accounts.
Usually, "emails to non existing email accounts" will either be configured to bounce or reject. However, what could be done If you need to receive any email sent to "anything"@example.com even if those email accounts do not exist. In such a scenario, you can set destination of "emails to non existing email accounts" as a forwarder to another email account.
If you decide to do this, consider forwarding email to another email account in this domain rather than forwarding them all to an external email account in gmail.com or yahoo.com or outlook.com. If you are wondering, why it is not recommended to forward email to an external account, please read the link: http://kb.bytehouse.co.uk/content/13/32/en/why-email-forwarding-or-email-redirection-to-external-email-account-is-dangerous-to-use.html
I am sure, you will now have a second thought about whether it is really required to catch emails to non existing accounts.
My recommendation is no as majority of the emails you are going to receive in the email account which is set as target of "emails to non existing email accounts" will be spam emails. Spammers are known to send spam emails to random email names of domains and if you setup a catchall, you will receive all these spam emails.
Now, the obvious question is, where can you find these settings in plesk.
Please see the procedure below.
1. Login to plesk
2. Go to Domains in left tab
3. Click "Open in Control Panel" button in right side of domain under concern
4. Go to Mail tab
5. Click "Change Settings" tab