Envelopes have been used as a method of mail delivery for centuries, but their origins remain a mystery.
Now, a team of researchers is bringing their expertise to bear in investigating the mysteries surrounding them.
A paper describing their research was published in the journal PLOS ONE on Tuesday.
Researchers from the University of Oxford, the University at Buffalo, the Center for Cybernetics at the University College London, the United Kingdom and the University in Paris, France, used a computer model to determine the envelope maker’s role in the distribution of envelopes in the modern world.
They found that most of the envelopes that had been used in the past were manufactured in one of two ways: by a mailmaker who left a mark in the envelope and then a person who left it to be opened by a stranger, or by a sender who left the envelope open and someone who opened it.
The paper’s authors found that the former was a far more common way of mailing envelopes than the latter.
“In terms of the nature of the marking, it’s not really an entirely new thing,” said co-author Mark Williams, a researcher in the School of Computer Science at the London School of Economics and Political Science.
“There are some pretty good evidence that mail-based mail is an old practice, dating back to the early 1500s, and there is a lot of evidence for it being used to send money or to deliver mail.”
Envelope makers who left marks in envelopes have historically been believed to be the perpetrators of the crime.
But the new study indicates that the mark-making technique used to produce envelopes is not a new phenomenon.
The researchers have also found that it’s possible for someone to make an envelope using an envelope maker who left no mark.
“You can have someone who doesn’t mark up a piece of paper or someone who makes an envelope by hand,” Williams said.
“They may be doing this for some other reason.”
Enamel stamping and other inkmaking techniques were discovered in the 1800s.
While stamping is the oldest form of mailmaking, inkmaking is not, and the paper used for those techniques was likely created by a person whose work was not of any importance.
The new study suggests that the modern envelopes may have been created by stampers who made marks on paper before inkmaking.
Williams and his colleagues say the paper is likely to be inks made from other materials.
“If you think of the history of ink, it was invented by the Romans and the Egyptians,” he said.
The authors suggest that these people may have made their marks with ink or other materials, but they did not mark them with ink that was then used for ink making.
They also believe the paper may have also been made by people who knew the ink makers, but who left their marks on it.
Williams believes that these marks may be evidence that the paper was marked with ink.
“The marks you see on the paper are the ink marks that the ink used to make the paper,” he explained.
“That’s probably how they were marked, and they were probably made by a stamper who had a mark on it that they were able to get rid of.”
In addition to the inkmarking technique, the authors also used computer models to examine how mail-delivery envelopes were made.
They compared the shapes of some of the marks that would be expected on the envelope to those on the actual envelope.
“We found that there was quite a lot more variation in the shape of the ink markings than we thought,” Williams explained.
This suggests that some of these marks were made using other types of marks that were also used in inkmaking, as well.
“What’s fascinating about these marks is that they look very similar to ink markings that we have seen in stamps and ink ink,” Williams added.
“I think this would be the first time we’ve seen ink markings in mailboxes that look similar to stamp marks.”
These ink marks were probably used to stamp the envelope.
The markings were also likely made with other types to ensure the envelope was not lost or damaged, Williams said, noting that these markings were likely applied by a sealer who worked for the mailman or postal worker.
“This is not just a stamp marking that was made with ink,” he added.
The scientists think the markings on the letters in the envelop might have been the mark of the sender, or someone else who knew how to make stamps.
The stamping technique was also used to mark the envelop by putting the letter in a marker or stamping.
Williams suggested that these markings were made with a material that would also be used in marking mailboxes, such as a “marking pencil.”
“I’d say it’s likely that stamping marks were used to write letters that were placed in the mailboxes or other places,” Williams continued.
“When we stamp mail, we write on a