In order to attract attention it's possible to enter a general comment at the customer file level (not specific to certain transactions).
To do so edit your customer account with the small blue pen, and fill in your comment:
This is displayed in yellow at the top of the customer file:
Need to do the same but about a contact? Also edit your customer account using the small blue pencil, and fill in your comment at the contact level, your comment will be displayed urder the e-mail address: