Using a comma to separate city from postcode [closed]

I've had an interesting discussion with a colleague around the usage of commas in an address within an email signature.

They claim commas should never be used to separate the city and the postcode. Whereas I believe it makes sense for it to be there as if I were to write a letter each part of the address would be on a new line.

What would be the best practice here? Some visual examples of how it's currently formatted:

Business Name, Address 1,

City, Postcode

---

Apple Sauce LTD, 5 Henry Street,

Manchester, JF34 7TP

I might also add that said colleague only has an issue with the comma being between the city and the postcode. The other commas placement are fine.

If you are treating your email signature as something that will more-or-less be fully or partially cut/pasted for your surface-mail address, you should format your address in the signature the way your national postal authority recommends. As you have used an address in the United Kingdom as an example, I conclude that you are in the UK, and thus that the Royal Mail’s guidelines govern. The addressing guide on the Royal Mail website says explicitly that commas and full stops should be omitted. On that page, there is also a link “Best way to write a UK address” (javascript on the page, not linkable) that will display an image of an ideally-addressed envelope. Following that pattern, I would format the sample addresses from your question as

Business Name
Address 1
CITY
POSTCODE

and

Apple Sauce LTD
5 Henry Street
MANCHESTER
JF34 7TP

As I am in the United States, I would follow the guidelines provided by the United States Postal Service, and format a US address entirely in block capitals, thus:

BUSINESS NAME
ADDRESS 1
CITY STATE ZIP

and

APPLE SAUCE INC
5 HENRY STREET
MANCHESTER NH 03101