The Recipient Filter page of Mail Options contains settings defining how different sets of recipients get PK Protect Attachments.
Encrypt message body and attachments
There will be people you correspond with that will always receive sensitive emails and attachments from you. To ensure that you always encrypt mail to those individuals, add their email addresses to the Encrypt message body and attachments when sending to the following recipients list.
This option is similar to the option above, but for recipients on this list, the email text is not encrypted. Only attached files will be encrypted.
Make a list of recipients who will receive all attached files compressed into a ZIP archive without encrypting anything.
Make a list of recipients who only get attachments that are neither compressed nor encrypted. These will be people you correspond with that will never see sensitive emails or attachments from you. Add their email addresses to the Skip actions when sending to the following recipients list. PK Protect will not prompt you to encrypt for these addresses. Be aware that large, uncompressed attachments may bump up against maximum attachment size limits for some email providers.
Be aware that if encryption is otherwise required for any single recipient (including inclusion on either the Encrypt Message Body or Encrypt Attachments list), PK Protect will bypass the Skip Actions list, and encrypt the data for every recipient.