To: addresses of form "lastname, firstname <name@addr.com>" cause MissingTo error

[mdharm]

When creating a message using Message::builder() and adding multiple To: headers of the format lastname, firstname <name@addr.com>, an Error::MissingTo error result is returned.

NOTE: This is different from #672 in that the issue is in how the address is parsed; in #672 the address is provided as

(Some(r#""Doe, Jóhn""#.parse().unwrap()),
        "john.doe@example.com".parse().unwrap())

but here I am using str::parse(), which is failing to detect the comma and MIME-encode the name portion. I suspect that a change in Mailbox::from_str() would be required.

This code snippit will demonstrate the issue:

use lettre::Message;

fn main() {
    let builder = Message::builder()
        .from("test@foo.com".parse().unwrap())
        .to("ln1, fn1 <addr1@foo.com>".parse().unwrap())
        .to("ln2, fn2 <addr1@foo.com>".parse().unwrap())
        .to("ln3, fn3 <addr1@foo.com>".parse().unwrap());

    println!("builder is: {:#?}", builder);
    println!(
        "result after calling body(): {:#?}",
        builder.body(String::from("Be happy!"))
    );
}

Running this produces:

builder is: MessageBuilder {
    headers: Headers {
        headers: [
            (
                HeaderName(
                    "From",
                ),
                "test@foo.com",
            ),
            (
                HeaderName(
                    "To",
                ),
                "ln3, fn3 <addr1@foo.com>",
            ),
        ],
    },
    envelope: None,
}
result after calling body(): Err(
    MissingTo,
)

If I remove the commas between the last/first names, I get the (much more reasonable):

builder is: MessageBuilder {
    headers: Headers {
        headers: [
            (
                HeaderName(
                    "From",
                ),
                "test@foo.com",
            ),
            (
                HeaderName(
                    "To",
                ),
                "ln1 fn1 <addr1@foo.com>, ln2 fn2 <addr1@foo.com>, ln3 fn3 <addr1@foo.com>",
            ),
        ],
    },
    envelope: None,
}

I'm not 100% certain what the "correct" behavior would be, but I would expect it to be something like:

            (
                HeaderName(
                    "To",
                ),
                ""ln1, fn1" <addr1@foo.com>, "ln2, fn2" <addr1@foo.com>, "ln3, fn3" <addr1@foo.com>",
            ),

This happens with Lettre version 0.10.0-rc.3

[kevincox]

I looked into this too and it appears to be that in the builder lettre mushes headers into a comma separated list. Then when it parses them back it does so simply by splitting on comma. It seems that there are a lot of assumptions baked in here and a quick look at the code gave no obvious fix.

[kevincox]

#698 was not enough to fix this. As a hack we could update the code to encode the , using base64 as if it was a disallowed character. IDK if this is a good idea but it would be a quick hack.

[paolobarbolini]

I'm thinking of merging #670 (did I miss something for not having merged it earlier?) and then write an hacky solution dependent on https://github.com/lettre/email-encoding while we figure out a clean solution for #693

[kevincox]

I don't think #670 is related but I would be happy to merge it. I'll leave a comment clarifying the state there.

I think a hacky fix would be nice. I am working around this my my code by running name.replace(',', "") but that is only really great for my use case. We shouldn't be "corrupting" user's requests silently.

[paolobarbolini]

I don't think #670 is related but I would be happy to merge it. I'll leave a comment clarifying the state there.

It's mainly to avoid the headache around merge conflicts and internal API changes

[paolobarbolini]

Should be fixed by #760

[kevincox]

Thanks, I can confirm that this fix is working!