A ‘Catch All’ email account is the account that captures emails sent to any invalid email addresses of the domain. When configured, the emails sent to any email address related to the domain, will not bounce back. Even it will deliver the email addresses to ‘non-existing’ or ‘invalid’ email addresses of the domain to the ‘Catch All’ account configured.

The administrator or the users who have access to the catch-all email account can validate the email. Also, they are able to resolve any typos in the email address or first name, last name confusions, and route the mail to the validated address.

Moreover, this also helps in preventing any important emails to the domain from bouncing back. 
For ex: If the user addresses a mail to abc_d@yourdomain.com instead of abc.d@yourdomian.com, the email will not get bounced. It will be in the catch-all mailbox. The administrator or the catch-all account user can easily validate and route the mail to abc.d@yourdomain.com.

‘Catch All’ further helps to discourage spam emails sent using a brute force method. This helps to classify the valid and invalid mail addresses of a domain by tracking the emails delivered and bounced back.