Add a test for an email with UTF-8 subject

[boris-petrov]

This test is not "complete". I think it's not supposed to work as-is. You see I set the Subject header directly with some Unicode symbols in it (because I don't want them to be encoded). Java Mail is supposed to support that with the mail.mime.allowutf8 property set. That's missing from the test - I'm not sure how to correctly set it here. But in any case - even with it set, still the resulting subject contains ??? (at least in my own tests). Not sure if I'm doing something wrong or that's an issue in Greenmail.

cc @marcelmay

[marcelmay]

All headers must be encoded, see https://www.rfc-editor.org/rfc/rfc2047 for details.

Could be done e.g. via

message.setHeader("Subject", MimeUtility.encodeText(subject));

or indirectly by using

message.setSubject(...)

Longer subjects (encoded >76 chars) need to be folded, too. Example from https://github.com/jakartaee/mail-api/blob/master/api/src/main/java/jakarta/mail/internet/MimeMessage.java#L874 :

		setHeader("Subject", MimeUtility.fold(9,
		    MimeUtility.encodeText(subject, charset, null)));

[boris-petrov]

@marcelmay thanks for the response. I obviously haven't read the RFC, however isn't the mail.mime.allowutf8 property exactly for that? Doesn't it allow setting UTF-8 symbols in headers without encoding first? That requires server support as far as I understand but otherwise it's supposed to work. Or did I misunderstand something? If I'm correct, then this test should work (after mail.mime.allowutf8 is somehow set - which I haven't done - please see my initial comment).

[marcelmay]

After diving into JavaMail sources this will only work if the SMTP server also announces SMTPUTF8, which GreenMail currently does not support:

https://github.com/javaee/javamail/blob/master/mail/src/main/java/com/sun/mail/smtp/SMTPTransport.java#L768 :

	    if (allowutf8 && !supportsExtension("SMTPUTF8"))
		logger.log(Level.INFO, "mail.mime.allowutf8 set " +
			    "but server doesn't advertise SMTPUTF8 support");

It is really mail server dependent. If I force the property, it shows up in the logs:

Feb 06, 2023 9:55:41 PM com.sun.mail.smtp.SMTPTransport protocolConnect
INFO: mail.mime.allowutf8 set but server doesn't advertise SMTPUTF8 support

I created #535 for SMTPUTF8. Though I believe not many servers support it ... ?

[boris-petrov]

No idea how many servers support it. And yes, I guess GreenMail also doesn't support that. But in any case, this is rather low-priority I would think. #481 and #483 are much more important.