My work e-mail repeatedly shows the message mailtips cannot be shown right now message why is that?

I have encountered this on many occasions. If i send to someone new this message appears and the request gets stuck in my outbox and is unable to send. The situation was rectified but only for a week. I attempted to send something to someone i normally do not send to and this has happened. The technicians said it is no big thing but i disagree. I am not a technical saavy person but i recognize an issue when i see it. It is a recurring issue.