Is it rude ....

[blessedbethechocolate]

...to resign by email?

I would normally hand in my letter of resignation but Covid is rife in my workplace at the moment so I'm not sure it's a good idea. Would it be wrong to email it instead?

You can send a formal email or better, send a formal letter as email attachment - I’ve both resigned this way and received resignations like that. Not a problem

Call, then email.

Not rude as such but is it possible to give your manager a quick phone call/conversation in person before the email or letter?
I think that would be more polite/appropriate unless there is a reason you can’t

That's the thing the only phone is in the main class and I don't really want everyone listening in to my business.

Email and arrange a phonecall out of hours to talk about a personal matter.

Last time I resigned it was by email. My manager knew I'd had an offer and a reference request was coming which I knew would be fine so it was all a formality. I think email is fine and arrange a private call as someone else suggested.

I sent an email. I didn't bother calling as l didn't get on with my manager (her doing as far as l was concerned) and l didn't owe her the courtesy imho.

Email is fine, I work in HR. We get email ones all the time.

Yes I would consider that to be pretty rude and I am sure most people I have ever worked with would too. An email to HR is totally different, you don’t hand your resignation in to HR, you hand it in to your manager. An email to confirm to HR afterwards is fine. To the line manager, a phone call if you can’t do it in person.