Pretty light on details. By "prefix", do they mean the local part of email address? Like the "someuser" in "someuser@example.com" ?

If so, it's not that unusual that it wouldn't be supported. The local-part used to be constrained to ascii only. RFC6530 (SMTPUTF8) added UTF-8 support, but it's optional. Google only started supporting it in 2014, for example: https://googleblog.blogspot.com/2014/08/a-first-step-toward-... Microsoft has support in some places, but not others, etc.

Correct, there's a Github issue linked[1] that shows åliå@test.com as an example.

1. https://github.com/charlesthk/python-mailchimp/issues/116

It looks like that has been fixed:

https://github.com/charlesthk/python-mailchimp/commit/5a4ed6...

It was just mentioned to confirm that it was the "local-part" that was in question.

The article notes that fixing it in the python client doesn't fix the upstream lack of support on mailchimp's back end.

This just seems to be a case of high expectations. Support of utf8 local-part is spotty across lots of providers and software.

> How can you run mail campaigns without access to these users? Ridiculous.

These users? You couldn't even email them from Outlook until just last year, 2016! How many users in the world would have accepted having an email account that no one using Exchange servers could handle? That cuts you (the user) off from hundreds of millions of people on corporate networks.

> That cuts you (the user) off from hundreds of millions of people on corporate networks.

Arguably an advantage.

It's not just Exchange. RFC6530 support is pretty spotty.

Fastmail, which is pretty popular here, only allows a-z0-9_ in usernames. I don't see a "250 SMTPUTF8" reply when I connect to their server and EHLO. So, it's likely they don't support it either.

I use Fastmail and have sent myself a testing email with non-ASCII emails, like with Korean or Chinese characters. So 안녕@mydomain works with Fastmail.

So apparently if you host your own domain with them they do?

However, they don't appear to support it for username@fastmail.com. Either for sign up, or for live delivery. http://imgur.com/a/Otf4f (see both images)

Try sending to 안녕@mydomain from a gmail account...it looks like they may not be supporting SMTPUTF8 correctly. Which could result in sending-to-yourself working, but not from an outside source.

I suppose... until you apply for a job and can't receive a favorable response because they're one of the many Fortune 5000 companies that use Exchange/Outlook somewhere in their infrastructure.

Not every one of my email-addresses is used in a business-context.

I had to reread some bits to figure out that they are talking about email addresses which MailChimp fails on if they contain non-ASCII UTF-8 characters in the user part of the address, not the actual email message.

For some reason this person calls an email address an email.

Maybe English is not their first language?

In Poland, for example, it's common to use the word "e-mail" when one means "e-mail address", e.g. "give me your e-mail".

Why is that important?

That blog post makes no sense until you substitute email for email address — non-ASCII UTF-8 characters in the body of an email is no problem provided the right encoding is used.

Perhaps other readers will find that useful to figure out the intended message.

> substitute email for email address

Language nitpick: that should be the other way around, for meaning roughly instead of in this expression. I guess this might be going the way of comprised of and the like (once considered a clear error, but now so widespread that it's considered pedantic to reject it).

You should be downvoted, you're right and the order they used is wrong and requires your brain to rearrange it. If op wanted to use that ordering they should have used "with" in place of "for".

A year or two ago Cory Doctorow asked MailChimp how to get a list of all the mail lists an address is on and they wouldn't help him with that. MailChimp claims to be against spamming, but if that were true, I think they would give users a management screen.

https://www.theguardian.com/technology/2015/nov/17/death-by-...

Frankly, I agree with Mailchimp. Giving access to that information raises privacy issues (someone could potentially see that I'm subscribed to an embarrassing newsletter our at least use that information in phishing or advertising). Additionally it's a product that doesn't provide much benefit to Mailchimp and their paying customers

I suspect they meant that you'd use a check to make sure that you are in receipt of email to the address you want to check; similar to reset your password email, click the link in the email to prove it's your own email address.

How is showing me the lists I'm on a privacy issue?

Doctorow was on over 3,000 lists. Unsubscribing was a lot of work. The cynic in me says that's how MailChimp wants it.

Might be hard technically as well. I suspect it isn't one huge database with a nice indexed query to return all lists associated with an email.

Even then this should be possible to gather quite quickly and if not they'd still be able to collect it in a batch job and send result later by mail.

Assuming a database or table per list owner, that's X separate queries where X is the total number of MailChimp customers. Don't see how that would be quick or easy. MailChimp says they have over a million customers.

MailChimps brief article about it: http://kb.mailchimp.com/accounts/management/international-ch...

"Note Although MailChimp can process UTF-8 characters in most parts of our application, we cannot process UTF-8 characters in your subscribers' email address prefixes. We do accept Internationalized Domain Name (IDN) servers, so it’s alright to have UTF-8 characters in the domain name.

For example, we’ll block direcciónelectrónica@domain.com because the international characters are in the prefix, but we'll allow an address like test@ñoñó1234.com, where the characters are in the domain."

A bigger issue for me is that our ERP doesn't use UTF-8 for emails. I don't recall ever being told that this was a problem for our user base. We have a large number of contacts in Europe who forego their accents for the ascii equivalent

Never seen an accent in an email. It probably never was possible.

Mail Chimp is not a great platform. There are better alternatives.