To know people working in a school helps in retrieving blue postage meters (even if I had to make long and vain explanation how something without a commemorative postage stamps could be useful to me... Only, the technology teacher understood quickly the illustrative logic on a meter).
Here is the result on a single week in March:
These illustrated meters are becoming very common. They are proposed by the machine sellers (read, in French, the ad page of Satas). From top to bottom, you can see here the logotypes of a city council (La Courneuve in Paris suburbs), a sport federation (Seine-Saint-Denis departmental soccer district - guess which teacher received this one?) and one of the main teacher union in France.
For private firms, I have a problem because I have more contacts with teachers than with the administrative part of the school.
But, why are they blue? Laurent Bonnefoy, a French specialist of the meters - he is a membere of the Académie de philatélie, brought back the reason on a mailing list: postal operators judged that blue is the more readable color for the sorting machines. In France, they appear on 15 July 2002 on a first set of franking machine linked to La Poste's servers. The color had been extended to new machines and for new postage contracts. Red is tolerated until the stocks are finished and all machine be connected.
On the Virtual Stamp Club, a question about the Why blue? brought back many examples of color exceptions in United States meter history, whereas Mr. Bonnefoy reminded that the color was decided at the Universal Postal Union. Red until the Beijing Convention of 1999 (RE306 article, point 2.2 for those who could retrieve the text), in application since 2001.
Outside philately, I advice the reading of a little book by French historian Michel Pastoureau: Bleu. Histoire d'une couleur.