I Have a Unicode Email Address

Zack Bloom
1 min readOct 31, 2016


You can reach me at ☞@zack.is

We have support for unicode domain names now, why not unicode email addresses? For a long time, the answer was the SMTP spec. Originally written by Jon Postel in 1982, the spec specifies that the ‘local-part’ of an email address may be composed of only:

Any one of the 128 ASCII characters (no exceptions)

Fortunately, this was extended by the SMTP Extension for Internationalized Mail in 2012. It added a capability identified as SMTPUTF8 to the already long list of features an SMTP server can advertise. If the server declares this capability, the client may use any UTF8 character in an email address.

Even better, support for it in Postfix, the most popular SMTP service, landed in 2014. Unfortunately, this support is not complied into standard Postfix distributions. Even worse, to my knowledge, no commercial email service supports it yet. I tried most of them.

To get support, I ultimately ended up setting up my own mail server (nod to HRC), using a version of Postfix I compiled to include support. My server studiously captures emails and forwards them to my standard Gmail account, which can seemingly successfully both receive and send these emails.

Can every email client send messages to this account? Almost certainly the answer is no. I wouldn’t be surprised if Outlook or Lotus 1–2–3 flat out crashed. But Gmail can, and I’m curious to see how far it can go.

If you’d like to reach me, send a note to 🎃@zack.is.