invite email is not being sent

I'm having a similar issue with a mail handler I'm using which is reporting that the body is not in the correct format. And it does appear to be correct about that. For some reason the message body is formatted as a string.

I applied the patch from comment #2 and got the error:

TypeError: mail(): Argument #3 ($message) must be of type string, array given in mail() 
(line 123 of core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php).

Looking at the InviteByEmail->send() method:

• \Drupal::service('plugin.manager.mail')->mail(...) is used to create a $message array
• \Drupal::service('plugin.manager.mail')->getInstance(...)->mail(...) is used to send it

The message array format is different between the two. The mail backend call \Drupal::service('plugin.manager.mail')->getInstance(...)->mail(...) expects the $message['body'] to be a string, not an array. The code in InviteByEmail->send() is using the correct format.

The error reported in comment #2 must be coming from a different piece of code.

To try reproducing the problem I installed the Symfony Mailer module. I got the following error:

TypeError: Drupal\symfony_mailer\Email::setLangcode(): Argument #1 ($langcode) must be of type string, null given, called in /var/www/html/web/modules/contrib/symfony_mailer/modules/symfony_mailer_bc/src/MailManagerReplacement.php on line 125 in Drupal\symfony_mailer\Email->setLangcode() (line 184 of /var/www/html/web/modules/contrib/symfony_mailer/src/Email.php)

InviteByEmail.php has the statement:

$message = $mail->mail('invite_by_email', $mail_key, $invite->get('field_invite_email_address')->value, $invite->activeLangcode, [], $invite->getOwner()
  ->getEmail(), FALSE);

The Invite attribute $invite->activeLangcode does not exist. This is why null is passed, producting the error.

I did not get an error with the Swift Mailer module.

A working solution could be created by using the system language code.

$language = \Drupal::languageManager()->getCurrentLanguage()->getId();
// Prepare message.
$message = $mail->mail('invite_by_email', $mail_key, $invite->get('field_invite_email_address')->value, $language, [], $invite->getOwner()
  ->getEmail(), FALSE);

However, there are other considerations.

The Mail API is used without a hook_mail() implementation. The Mail API uses hook_mail() to populate the subject and body of the message. The current code works around not having hook_mail() by populating the subject and body after calling \Drupal::service('plugin.manager.mail')->mail(...) with the no-send option. After adding the subject and body the message is then sent by directly calling the mail backend with \Drupal::service('plugin.manager.mail')->getInstance(...)->mail(...).

There's a problem with this implementation: hook_mail_alter() is run when the $message array isn't fully populated.

hook_mail_alter() is run in \Drupal::service('plugin.manager.mail')->mail(...). The current code populates the subject and body after calling \Drupal::service('plugin.manager.mail')->mail(...). There is no way for other modules to view or alter all of the message values.

Regardless of the original problem, I think the current implementation needs changing in one of two ways:

1. Change the code to directly use the mail backend so hook_mail() is not required
2. Change the code to fully implement hook_mail()

For me, option 2 is the preferable solution.

Regarding the original problems reported, more information is needed.

Created a new issue for the hook_mail() discussion at #3275572: Implement hook_mail()

The hook_mail code has been commited to the 8.x-1.x-dev branch. If this doesn't solve the mail issue, it certainly changes the conditions that would cause it.

Please try out the 8.x-1.x-dev version and let us know if the error is still occurring.

If the error is still happening, please check the Drupal error log at Administration > Reports > Recent log messages for an error message and send us a copy if you find one, along with any other information you think might be useful.