I would like to know if there is a default password for the email used in document library and list for incoming mail, I'm developing an email listener and I need the mail address of the list and its password
The is no password for list email addresses because they are no associated with AD user accounts. There is also no inbox because these are not Exchange email addresses. List email addresses act more like identifiers for the lists so SharePoint knows where to direct and store incoming email messages.
You should have a connector in Exchange that routes emails sent to list email addresses to SharePoint, so the destination of the emails sent is never an Exchange mailbox, but SharePoint which converts the emails into list items.
I never came across a project where I needed to intercept emails sent to SharePoint lists, but I guess you can add an event receiver to the list to catch when a new item is created from an email.