incorrect display of mail due to outdated version of PHP mailer

[studiodv]

Good morning,

I am experiencing problems when displaying order confirmation emails and contact forms from multiple WordPress websites.

This code is displayed first in the emails:
Content-Type: text/html; charset=UTF-8

I've already been looking into what could be causing it. There it was indicated that it was due to the PHP Mailer version of WordPress. Could it be that the PHP Mailer update is not current with the new version (6.4.3) of WordPress?

Yours sincerely,
Diana

[sabernhardt]

Hi and welcome to WordPress Core Trac!

There it was indicated

Could you share a link to the explanation that this issue is related to PHPMailer?

If PHPMailer 6.8.1 is the cause, it could be resolved soon. WordPress 6.5, expected to be available later this month, will have the latest PHPMailer 6.9.1 (#59966).

I have seen a different issue with Content-Type headers in an old version of an SMTP plugin. If you have an SMTP-related plugin, I think that is another possible cause.

[studiodv]

Good afternoon,

Thanks for your comment.

I came across the message regarding php mailer here: ​https://github.com/PHPMailer/PHPMailer/discussions/2780

I use 1 plugin to display sent emails in the dashboard of the website. This is the WP Mail Logging plugin (version 1.12.0) from WP Mail Logging Team. With this plugin, the emails are not sent, only displayed in the dashboard, which is why I suspected that this was not the problem.

Kind regards, Diana Vlastuin

[SergeyBiryukov]

Thanks for the follow-up!

Replying to studiodv:

I came across the message regarding php mailer here: ​https://github.com/PHPMailer/PHPMailer/discussions/2780

That issue appears to be specific to PHPMailer version 5.0, whereas WordPress 6.4.3 uses PHPMailer 6.8.1 (#59238), so something else might be at play here.

[studiodv]

Thanks for your reply. So you don't think the problem could be related to WordPress? Or the plugin I installed?

I have also contacted the theme developer, but I have not received a response from them yet. Perhaps it could be due to the theme. I use the Kallyas Theme for all my websites and the problem occurs on several websites, so this is also a good option.

Thanks again.

Kind regards, Diana Vlastuin

[sabernhardt]

The support forum for WP Mail Logging has two topics related to the PHP headers:

• ​https://wordpress.org/support/topic/resending-sends-as-raw-plain-text/
• ​https://wordpress.org/support/topic/some-resent-html-emails-sent-as-plain-text/

Could you confirm whether updates to the plugin have resolved this?

[SirLouen]

@studiodv are you still experiencing the issue nowadays with the current version of WP (6.8.2)

Please provide the full raw original email version in case you are still experiencing this.

Judging by the PHPMailer report you mentioned, it seems there could be an issue with multipart emails you could be sending, but I need to see the raw email before reaching a conclusion.

[SirLouen]

Given that no answer has been provided for more than a month, and probably this is correlated with the multipart topic being already solved in #15448, it's time to close this as invalid.