bkaradzic / go-emailvalidator Goto Github PK

1. Using RFC822, RFC2822 headers themselves have been limited to ASCII, this means addresses with + or ' should be supported by any current MTA doing SMTP or ESMTP.
2. The textual part of the headers is being supported by RFC2047. This makes it possible to have Jøhn Døe <[email protected]> as an email address. This applies to From/To/Subject parts, but only the textual aspect, not the header itself.
3. For international domain names RFC5890 and RFC5891 come into play. This allows domains to be written in another script to be converted to ASCII-safe IDNA (commonly known as Punycode), i.e. 日本.jp (as U-label; how the user sees it) becomes xn--wgv71a.jp (as A-label; how the system interprets it). So this means that email to email address ichiro.yamamoto@日本.jp (as the user enters it into your system) will be sent email to [email protected]. Unless the entire system supports UTF-8 DNS, then everything is done using full UTF-8 strings.
4. For the case where the headers themselves allow accents or other scripts the intermediate MTAs need to support SMTPTUF8 (RFC6531). For the MUAs RFC6532 needs to be implemented. This allows the possibility of having an email address such as 山本一呂@日本.jp. As far as I understand it, this will be changed to either 山本一呂@xn--wgv71a.jp for transport or kept as is depending on the domain registration.

1 and 2 are active now on the Internet.
3 depends on the availability of an IDNA-compliant DNS resolver.
4 is future music, but Google Mail already supports it (http://googleblog.blogspot.be/2014/08/a-first-step-toward-more-global-email.html) and Postfix has it in development for 2.12 (http://www.postfix.org/SMTPUTF8_README.html), so it's sort of already here.

I left aside the issue of IDN ccTLDs, but it follows the same rules as domain names.

Not a huge issue, but you seem to do an O(N) lookup for no good reason. Using a map[string]struct{}{} would be more efficient, as you don't need to look through the whole array for a match.

Check out: https://github.com/lavab/disposable/blob/master/.generate/generate.go