Swiftmailer Swift Mailer

By historical silly misunderstandings, some of Japanese cellphone carriers (NTT Docomo and KDDI au, No.1 and No.2 market shareholders) introduced RFC violated mail addresses. Even they fixed it for new registration, they are still widely used.

1) Local part begins with period

.foo@example.com

2) Local part ends with period

bar.@example.com

3) conseqtive periods in local part

ba...z@example.com

All of above do not follow RFC2821, so giving those mail to Swift Mailer throws Exception.

MTA

But are they transferred properly? It depends on MTA. On Japanese part of the internet, they are usually accepted and transferred, because hundred of thousand such users exist.

How other mailers treat it

iPhone

When you tries to send to those address on iPhone, it pops up warning dialog. But you can proceed to send them.

Outlook

Outlook make it strict from Service Pack 3 and now you cannot send to those mail addresses.

Gmail

Google once introduced strict RFC filter, but now supports those format addresses if the receipients' domains are NTT Docomo or KDDI au.

Possible Fixes

I think it is a business and marketing decision so just list up fix options and want core team to choose.

1) change filter and always accept them

As your products and services can be used by Japanese with their cellphone address, it is one option to make them accepted by all Swift Mailer users.

Pro: - all Swift Mailer user applications are Japanese market compliant Con: - everyone should make effort to follow the standard way - invalid mail may cause with others if the application developer does not know it

2) add "Japanese cellphone mode"

If you turn it on, it accepts those bad addresses.

Pro: - only people who suffers the issue uses it Con: - the libary will not be "out of the box" for Japanese users

2-a) set it by constructor

2-b) set it by calling method after instantiaion

attached test code suggests this (method acceptJapaneseCellphoneAddress)

2-c) set it in configuration file

If a library user wants "warning", it is good if Swift_RfcComplianceException has more info, or specific subclass for "invalid RFC, but valid as Japanese cellphone address". Then it is possible for users to differenciate procedure afterwards. But it is not so mandatory as this can be also done outside of library before calling Swift Mailer.

And what to accept if the mode is set.

i) accept all of those invalid local part

ii) accept mail addresses by carriers who allowed invalid address

like what Gmail does. The patters are, as far as I know,

• (local-part)@docomo.ne.jp
• (local-part)@ezweb.ne.jp
• (local-part)@[a-zA-Z0-9_]+.dion.ne.jp
• (local-part)@[a-zA-Z0-9_]+.auone-net.jp

I attached an unit test code.