Attachment (file)names with special characters should not be encoded

[barkep]

When adding an attachment:
Testowy_załącznik_ąśćńółęĄŻŹĆŃÓŁĘ.txt
to an email and positive delivery, the recipient receives the attachment with the changed name:
=UTF-8_Q_Testowy=5Fza=C5=82=C4=85cznik=5F= =UTF-8_Q=C4=85=C5=9B=C4=87=C5=84=C3=B3=C5=82=C4=99=C4=84=C5=BB_= =UTF-8_Q=C5=B9=C4=86=C5=83=C3=93=C5=81=C4=98.txt_=.txt

After a small investigation, I find that the reason for this is using
MimeUtility.encodeText (name, UTF_8.name (), "B")
for the name of the attachment. I suggest using one of two solutions:

• adding a parameter that allows you to skip this action for attachments
• skipping this action for attachments

[bbottema]

This is valid encoding according to the RFC, but the client seems to parse it incorrectly. In what email client does the recipient view this result?

[barkep]

The attachment has an incorrect name directly, for example gmail.com.
The characters in the file name are important.

Sample code reproducing the error.

        String host = "smtp.gmail.com";
        int port = 587;
        String name = "";
        String password = "";
        TransportStrategy transportStrategy = TransportStrategy.SMTP_TLS;

        String path = "E://Testowy_załącznik_ąśćńółęĄŻŹĆŃÓŁĘ.txt";
        File file = new File(path);
        DataSource ds = new FileDataSource(file);

        Email email = EmailBuilder
                .startingBlank()
                .from("")
                .to("")
                .withSubject("test")
                .withAttachment("Testowy_załącznik_ąśćńółęĄŻŹĆŃÓŁĘ.txt", ds)
                .buildEmail();
        Mailer mailer = MailerBuilder
                .withSMTPServer(host, port, name, password)
                .withTransportStrategy(transportStrategy)
                .buildMailer();

        mailer.sendMail(email);

[bbottema]

Also see: https://javaee.github.io/javamail/FAQ#encodefilename

I'm going to turn off encoding of filenames, while making sure file names are tested for injection attacks.

[bbottema]

Fix released in 6.3.2

[LevStolpner]

@bbottema
Hi!
Thanks for this fix, was waiting for this update.
I have a related question regarding EmailConverter.
I wanted to check in test attachment file names, and was using method mimeMessageToEmail.
It was not working, I checked the call chain, and it seems that method buildEmailFromMimeMessage takes ContentId as attachment file name instead of actual not-encoded filename.
Is that a bug, or maybe I am not using EmailConverter correctly?