One purpose of a traditional memo or e-mail is to provide essential information quickly and easily, so there is no restriction, other than appearance or practicality, on the number or variety of guidewords you include.

Heat until the liquid bumps, then reduce the heat and continue the boiling for 1½ hours.

The party to this agreement may use the property whensoever and howsoever he or she pleases.

Where billow meets billow, there soft be thy pillow; / Ah, weary wee flipperling, curl at thy ease!