Details are hazy as this was a long time ago, but at some point you could make parts of messages not render in Outlook and Outlook Express by writing "begin something" (two spaces after "begin") by itself in a single line. Outlook would thing that it was the start of an uuencoded block and not render anything after that.
I remember annoying friends in a mailing list by quoting emails with "begin quote from Person Name:" :)
And to be fair in normal English orthography the word begin is never followed by two spaces. This is more like Microsoft wanting everyone to write proper English than Microsoft wanting to change the English language
I have vague memories of it being a Microsoft thing to insert two spaces at the end of every sentence? I could be misremembering.
The bug here was not "begin" followed by two spaces, but rather its "begin" followed by some other text followed by two spaces, which if i recall correctly is exactly what Microsoft would auto-format your text to.
I don't like Excel, but 1) it is a true feature when used as intended in a finantial environment and 2) you shouldn't use Excel to fiddle with genetic data, learn proper tooling, you are supposed to be a pro. Still I think changing user data silently is an error.
This is known since at least 2004, with workarounds (https://link.springer.com/article/10.1186/1471-2105-5-80), yet people still use Excel instead of learning a bit about proper data storage. In my lab I sent a mail with the steps to harden Excel against this "bug". Want to guess how many did it? Zero.
Excel is second after Access for bottom-up developed data storage. And since Access is all but gone, it's absolutely not surprising people reach for Excel.
The unix mbox format uses the sequence ["F", "r", "o", "m", " "] as its indicator that a new mail has started. If you're not careful about escaping your stored mails, you can easily corrupt them by starting a body paragraph with the word "From".
How do you escape the word From? Well, that's up to the client! Be careful using different clients for a given mbox file!
The fun part is that the actual uuencode format has the file mode in octal after the word begin. Somebody at microsoft decided this was optional and that begin with two spaces and then the filename should also be the start of a uuencoded section. Of course also without checking if there was any content that was actually encode in that format.
I remember annoying friends in a mailing list by quoting emails with "begin quote from Person Name:" :)