If an administrative assistant receives a negative or lukewarm letter of recommendation, they should consider not submitting it with their job application. They could instead request a letter from a different reference who can provide a more positive endorsement. Alternatively, they could have a conversation with the reference writer to see if there are any specific areas for improvement they could work on in their job search. It is important to remember that not all letters of recommendation will be glowing, but it is better only to include ones that will strengthen the overall application.