Mail Server Error 5.1.3 on Int'l Addresses

software development



I am using my virtual DH mail server (i.e., ‘’) from a Zend_Mail script with UTF8 and base64 header encoding to send out notifications. Apparently, I can go crazy on the local part of a recipient’s address, but internationalized domains (e.g., @郵件.商務) yield a ‘5.1.3 Bad recipient address syntax’ error. Is there anything else I can do from my end, or does DH’s mail system not allow for int’l addresses yet?




Email addresses have to be converted from Unicode to ASCII before they can be used in mail. (This is not specific to DreamHost; it’s just usually handled for you by email client software.) For instance, the address you mentioned, username@郵件.商務, would be represented as username@郵件.商務.

In PHP 5.3 and later, you can perform this conversion using the idn_to_ascii() function.



Fast and relevant reply as always. Thanks a bunch! Is this something that will eventually be implemented on the system level, or is this where we’re at for the foreseeable future? The Wikipedia entry on the latest developments in internationalization of e-mail addresses doesn’t really give reason for hope :slight_smile:

Bests, Mike
Ok. Please disregard my previous question. According to this

it’s more of a DNS problem than anything else.

Bests, Mike


PS: looks like idn_to_ascii() doesn’t exist under my shared 5.3 setup. Am I missing a module here?

Thanks, Mike


Ok. I really need to stop replying to myself, but maybe this could be of help to someone else :slight_smile:

Looks like both the ‘intl’ and ‘idn’ extensions need to be installed for php’s idn translation functions. On my hosted 3.5 setup only ‘’ appears to be available, so still no go. As a workaround, I’ve found the ‘Net_IDNA’ library, available here:

Seems to be working – at least the mail server stopped yelling at me…