The postal rates and regulations in effect during the Eagle period was more or less the exact same as those introduced on February 21 and December 15, 1856, when the first Mexican stamps were issued.

The Mexican postal service handled everything from simple letters to mining equipment and agricultural products. Only simple letter correspondence is treated here, thus excluding rates for special services such as lotteries, charities, educational and political material.

Weights and measurements


Until the French Intervention, Mexico had been using the old Spanish currency where one Peso was divided into 8 reales, thus one real was 1/8 of a peso. This same currency was used in the U.S. with the name changed from Peso to Dollar.

Maximilian's government introduced the decimal system, whereby a peso was divided into 100 centavos. That change was cause for great confusion, since not enough of the new currency was available. This new currency was mandated for use by the postal department, but made it difficult to pay for ½ and 1 real stamps, since they now cost 6.25 and 12.5 centavos respectively. There were no fractional coins, so the actual price was often set by the postal clerks. Considering that newly occupied territory had none of the new currency, it's easy to imagine the kind of trouble this change in the monetary system must have caused.

The peso nominally weighed 550.209 Spanish grains, which is 423.9 troy grains or 27.468 metric grams, 93.055% pure. It therefore contained 25.560 grams of pure silver. Its weight and purity varied significantly between mints and over the centuries.

The peso coins were often physically cut into eight "bits", or sometimes four quarters, to make smaller change. This is the origin of the name "pieces of eight" for the coin, and of "quarter" and "two bits" for twenty five cents in the U.S.


Weight was measured in troy ounces (onza, onzas), corresponding to 30 grams, a measurement not like any of today's troy or avoirdupois ounces. There was no correlation between the Mexican ounce and an ounce as defined by other countries.


Distances were measured in leagues (leguas), where one legua = 5000 varas = 4180 meters = 2.6 statute miles. 17 leagues therefore correspond to about 44 miles.

Simple letters

Weight Distance less than 44 miles Distance over 44 miles
0-½ ounce 1 real 2 reales
½-¾ ounce 2 reales 3 reales
¾-1 ounce 3 reales 4 reales

This progression, charging 1 real per ¼ ounce, continued up to 10 ounces (300 grams). Letters weighing more than 10 ounces were charged ½ real per additional ¼ ounce.

For example, a letter weighing 2 ounces to a destination 50 miles away would have been charged as follows:

  • 2 reales for the first ½ ounce
  • 6 reales for the next 1.5 ounces (1.5 * 4 quarter ounces = 6)

Total cost would therefore have been 8 reales.

Correo Extraordinario

As early as 1580, a special rate for mail between Mexico City and Veracruz was instated. The idea was to ensure delivery of mail to departing ships within 36 hours of departure, and often managing to actually deliver in as little as 24 hours. The rate was determined by a postal official, but usually amounted to double the normal rate plus an additional ½ real "port tariff". This fee was presumably charged for delivery from the post-office to the ship, but may have been a payment to the ship's captain for handling the mail.

Very little is known about this service, and existing covers are very scarce. However, this service was also used for mail from Vercruz to Mexico, and it appears that the ½ real fee was not charged in this direction, giving some credit to the theory of a "port tariff". The "Correo Extraordinario" enabled businesses in Mexico City to get advance notice of news from the outside World before any others.

It is possible that the high ratio of 4 and 8 reales stamps used from Mexico City and Veracruz was due, in part, to this special service. In Veracruz about 12 ½ real stamp were used for every 15 8 reales stamps, while in Puebla the ratio was four ½ stamps for every 8 reales stamp.

Registered letters

Special low rates were in effect to other Latin American countries, but no such correspondence is known to exist today.

Unsealed commercial announcements

Sent individually at a cost of medio real each. Bundles of 100 were charged at 32 reales.

Commercial announcements were very important at a time where the mails was the only far reaching form of communication. Businesses sent them to inform their customers of important news, for example about new ownership or change of management. This was the state-of-the-art customer relationship tool at the time. These letters are very scarce today, since they were often discarded by the recipient.

About half of all the announcements were sent without stamps (Sellos Negros), and only about two thirds of the rest were franked with ½ real stamps, the other third being accepted and paid for, but without attaching stamps.

Over half the "unsealed announcements" were actually sealed, and therefore not truly eligible for the ½ real rate.

Perhaps 20 or 30 are known with Sellos Negros, and only about half that number have survived with a ½ real stamp attached. Only one example is known with a bisected 1 real stamp to cover the rate.

Ocean mail

During the Eagle period, new rates were in effect for Ocean mail to foreign destinations. The basic rate was 2½ reales for ½ ounce to U.S. destinations, and 4½ reales to European destinations. Only one cover is known to exist today.

Soldier's mail

European volunteers

King Leopold of Belgium and Emperor Franz Josef of Austria provided Maximilian with "volunteers" for his campaign in Mexico. They were afforded a special rate of ½ real for a ½ ounce letter sent from Mexico to Europe. Additional fees had to be paid in Europe by the recipient. Three letters are known sent to Austria, three to Belgium and maybe three or four to other destinations in Europe.

French Foreign Legion

It is possible that the French Foreign Legion could send letters free of charge from Mexico to Europe, but no letters are known today, which could prove or disprove this theory.