The mail_server role implements full functionality for setting-up an SMTP/IMAP server. The implementation requires user to authenticate both when using the SMTP and IMAP.

However, the way the mail server (Postfix) is currently set-up, it is trivial for authenticated user to provide any e-mail address as the sender - there is no validation on whether the logged-in user's e-mail address matches to the sender address advertised by the mail client.

This type of forging can be easily prevented through additional configuration.

The following should be done:

• Update the mail_server role.
  • Configure Postfix to prevent forging of sender addresses for logged-in users. For implementation se the Protecting against forged sender addresses section of the workaround.org guide.
• Update role reference documentation.
• Update usage instructions.
• Update release notes.