[quesera]

This happens in the US too, and even if you're wise enough to treat postal codes as strings (which they are) and not integers, someone is going to paste the data into Excel which will promptly blow things up on you anyway.

[Breza]

Head of data science at a corporation here. People pasting into Excel has been a bane of my job for over a decade.

[quesera]

Yes! I'm sure you know this, but for anyone with similar problems:

You can disable this conversion "feature" in the Excel "Automatic Data Conversions" preference pane.

...and I hope you have better luck getting people in your company to remember this than I have! :)