It isn't very clear to me if this is the correct request or if https://protonmail.uservoice.com/forums/945460-general-ideas/suggestions/45849907-change-username is more appropriate, but here it is.

According to:
https://proton.me/support/change-username
(archived) https://web.archive.org/web/20250803180251/https://proton.me/support/change-username

"When you created your account, you also created a key that was matched to your username. This key allows you to send and receive emails using Proton Mail’s encryption. Changing your username would change the key that was used to send and receive all the emails in your inbox."

Presumably, this is not referring to the PGP key, but a different key. Regardless, however, this explanation does not make sense. Why does that prevent anyone from changing their username?

Think of it like this. Let the following variables exist:
O - the original username
N - the new username
o - the key derived from the original username, "O"
n - the key derived from the new username, "N"
D - the data that is encrypted/decrypted with the username-derived key, in plaintext form
X - the aforementioned data "D", as encrypted by the key derived from the original username, "o"
Y - the aforementioned data "D", as encrypted by the key derived from the new username, "n"

Because the data "D" is encrypted with the key "o", there must exist a function "e_o", where e_o(D) = X.

Similarly, because the encrypted data "X" is decrypted with the key "o", there must exist a function "d_o", where d_o(X) = D.

Given that I could create a new account using the new username "N", it must be possible to achieve similar functions with the key "n".

This means that there must exist a function "e_n", where e_n(D) = Y. There must also exist a function "d_n", where d_n(Y) = D.

Now, in order to change my username from "O" to "N", starting with the data "X" (which is encrypted using the key derived from the original username), all that must be done is the following:

1. d_o(X) = D
2. e_n(D) = Y

That's it. We're no longer reliant on the old key and can switch to the new key.

Given that Proton's services are End-to-End-Encrypted (E2EE), most if not all of the processing of this data should be happening on the user's device anyway, so the load on Proton's side should be minimal.

This doesn't require some insane technical feat of cryptography - all the tools already exist. They MUST exist by the fact that Proton's services work at all to begin with.

More importantly, however, is the fact that I contacted support about this already, requesting more details on why exactly it cannot be done. Despite reiterating that I understand the CLAIMED reason, "we derive a key from your username", I was told TWICE that the main reason was that "we derive a key from your username", completely ignoring the explanation as to why this "reason" doesn't seem to hold water in the slightest.

It could be a paid feature. It could have a 3 year cooldown. It could require typing out confirmation that loss of power could result in permanent data loss. There could be as many roadblocks as you want, but fundamentally, there's no clear reason why it isn't possible.

Most frustrating about all this is the lack of transparency. If there's a genuine technical reason, I'd love to be enlightened on how such a thing could even be possible. I feel quite confident it isn't possible for such a thing to exist, given how simple the idea of "just decrypt and encrypt" is.

If there's a different reason, just say so. Don't lie. Don't hide. If there's no reason other than "we don't feel like it", say so.

I pay for Unlimited because I expect better from Proton.

I want ability to change my username, even if it takes couple of days to reencrypt all data, event if it costs some money to process it, event if it will reencrypt data in boundaries of my computer.

I think we should be able to change our username or email address to something that hasn’t been used by someone else. For example:

Your current ProtonMail email is: protonuser@proton.me

But you want to change "protonuser" to "protonlover." Right now, you cannot change your username or address either. You must create a new account and move everything to the new account. This results in a lot of lost time and challenges.

So I think we should be able to change the username (the left side of @) and @proton.me or @protonmail.com without having to create a new account.

protonuser@proton.me -> protonlover@protonmail.com

Or

protonuser@proton.me -> protonuser@protonmail.com

Or

protonuser@proton.me -> protonlover@proton.me

Protonmail have said that this isn't possible, but it's unclear to me whether that is a business decision or a theoretical impossibility. They mention authentication keys but I'm unclear why they can't just unencrypt then re-encrypt everything with a new key. If it actually is theoretically impossible (rather than just technically difficult) it would be good have that mentioned somewhere

I want to change the username of my account

I want to change the username of my account

Somehow my account has gotten on a list that is sending me solicitation emails to my primary account. If I cannot change my username I am willing to create a new account but I am a paid subscriber with two personal domains setup. I am OK with setting those back up on the new account but I really need to do away with this account so the email stop coming to me. If I cannot not change my username can I move my paid subscription to a new account?

agree

I'd like to be able to change my current xxx@protonmail.com address to xxx@protonmail.ch without getting a new username.

What if one's username reflects a legal/given name, and one is transitioning (transgender)? Can we possibly change the username to reflect our "preferred" email address / alias?

+
Can *@protonmail.com can be linked to *@protonmail.ch - for those who prefer the Swiss extension, or is that not possible?