Why can we not send base64 data as attachment without either uf8 encoding it, or breaking html body?!

[smileBeda]

let base64Encoded = signedData.base64EncodedString()

        let gpgAttachment = Attachment(
                data: Data(base64Encoded.utf8),
                mime: "application/octet-stream", // or "application/octet-stream"
                name: "\(title).pdf.gpg",
                inline: false,
                additionalHeaders: [
                        "Content-Transfer-Encoding": "base64"
                    ]
            )
        
        let mail = Mail(
            from: from,
            to: [toUser],
            subject: emailSubject,
            text: "Please use a HTML ready Mail Client to view the email.",
            attachments: [
                Attachment(
                    htmlContent: htmlContent,
                    additionalHeaders: ["Content-Type": "text/html; charset=utf-8"]
                ),
                gpgAttachment
            ]
        )

The above works:

• HTML in email will not be broken
• file will be attached

BUT:
since file is a SIGNED file (thus a .gpg file), the above code will BREAK the signature as we encode it to utf8 and that messes the signature up

Thus:

let gpgAttachment = Attachment(
                data: signedData,
                mime: "application/octet-stream", // or "application/octet-stream"
                name: "\(title).pdf.gpg",
                inline: false,
                additionalHeaders: [
                        "Content-Transfer-Encoding": "base64"
                    ]
            )

File will now validate correctly (PGP signature valid) but this will mess up the HTML part of the mail rendering it gibberish like v�-蕳《ia秈q歒���m��鹈7⒏?走}�etc etc

There must be something I miss.

[smileBeda]

And why is no html parameter supported?
I mean, passing the HTML content as an attachment is about as wrong as it gets?

What do I miss?

[smileBeda]

Basically you are sending attachment in BASE64 no matter what despite this:

let htmlAttachment = Attachment(
            data: htmlContent.data(using: .utf8)!,
            mime: "text/html; charset=utf-8",
            name: "body.html",
            inline: true,
            additionalHeaders: [
                "Content-Disposition": "inline",
                "Content-Transfer-Encoding": "7bit"
            ]
        )

It results in

SEND: --9F8A768CD6044BBC894458D9CFC154FF
SEND: CONTENT-DISPOSITION: inline; filename="=?UTF-8?Q?body.html?="
CONTENT-TRANSFER-ENCODING: BASE64
CONTENT-TYPE: text/html; charset=utf-8

And that is just wrong.