ESA - Configure DKIM Signing
- Create a DKIM signing key
- Generate a new DKIM signing profile and publish the DNS record to DNS.
https://www.cisco.com/c/en/us/support/docs/security/email-security-appliance/213939-esa-configure-dkim-signing.pdf

1) Click Security Services > Scan Behavior.
2) Define the attachment type mapping.
3) Configure the global settings.
4) Edit the required fields:
Action for attachments with MIME types
Maximum depth of attachment recursion to scan
Maximum attachment size to scan
Attachment Metadata scan
Attachment scanning timeout
etc...
https://www.cisco.com/c/en/us/td/docs/security/esa/esa11-1/user_guide/b_ESA_Admin_Guide_11_1/b_ESA_Admin_Guide_chapter_01000.html?bookSear ch=true

https://www.ciscolive.com/c/dam/r/ciscolive/us/docs/2019/pdf/BRKSEC-2240.pdf

Enabling End-User Quarantine Access and pointing to an LDAP server for authentication is the action that must be taken to meet this requirement. End-User Quarantine Access is a feature that allows users to access their personal quarantine on Cisco ESA using their email address and password, without requiring an administrator account or access to Secure Email and Web Manager. To enable End-User Quarantine Access on Cisco ESA, the administrator can follow these steps:
Select Security Services > IronPort Anti-Spam > End User Safelist/Blocklist Settings and click Edit Settings.
Under End User Quarantine Access, select Enable End User Quarantine Access. Under Authentication Server, select LDAP Server from the drop-down menu and choose an LDAP server profile from the drop-down menu.
Click Submit.