Support headers for native_mailer

[nalysius]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no
Symfony version	4.1
Monolog Bundle version	3.3

I am currently using Monolog to receive mails when I log errors. With the swift_mailer handler I don't receive any mails using sendmail transport. I am used to use NativeMailerHandler with Monolog so I would like to use it as handler. With native_handler I receive emails, but they are always in plain text.

The swift_mailer handler does support a content_type key that allows to get the mail as text/html.

The NativeMailerHandler class has a headers attribute that could contains a content-type. For now only swift_mailer is able to send email as html, native_mailer doesn't use any 'headers' or 'content_type' keys.

The following example would be fully compatible with swift_mailer.

monolog:
    handlers:
        main:
            type:       native_mailer
            from_email: 'myemail@example.com'
            to_email:   ['user@example.com']
            subject:    'An error occured'
            level:      error
            formatter:  monolog.formatter.html
            content-type: text/html

But this one would be more flexible with the usage of headers.

monolog:
    handlers:
        main:
            type:       native_mailer
            from_email: 'myemail@example.com'
            to_email:   ['user@example.com']
            subject:    'An error occured'
            level:      error
            formatter:  monolog.formatter.html
            headers:
                content-type: text/html

[lyrixx]

Hello @anthonybocci

Would you mind to submit a PR?

Thanks

[nalysius]

Hi @lyrixx,

I just submitted a PR.
It works, but since it's my first contribution please let me know if something is wrong or missing.

[ilya-realforce]

@nalysius sorry for necro-posting, but were you able to override the Content-type header? I couldn't do that, because with config's headers part you only can add new headers (since NativeMailerHandler.php:96 is only appending new items to the headers array), and on the NativeMailerHandler.php:122 there is no checking of existing Content-type header. It just adds text/plain unconditionally. As a result, I'm getting these headers in the mail:

Content-type: text/html; charset: utf8\r\n
Content-type: text/plain; charset=utf-8

I think the possible solution is to add content_type config key support somewhere around monolog-bundle/DependencyInjection/MonologExtension.php:543 and call setContentType of NativeMailerHandler with it.

@lyrixx can you also look at it, please?

[nalysius]

@ilya-realforce I am currently using the Content-Type header in several applications. In the mail's source I saw the same, the Content-Type header is present twice in the mail. It's not ideal.

Monolog handles the content-type in a special field, so even if we give it a header it will then use the content type and add it as a header. I guess it would be better in monolog-bundle to add a condition and check whether the header we are setting is the content type and if so call the method setContentType instead.