Improve error handling when sending emails

[rabauss]

Unfortunately, errors when sending emails are not handled correctly, so the sender will see the success page, although an error occured.

The hook pocessFormData will only stop with exceptions:
https://github.com/contao/contao/blob/2f1827b8a2cac27d2b86d7ba6337470217d6c60d/core-bundle/src/Resources/contao/forms/Form.php#L563

But the NC catches all exceptions when trying to send emails:

contao-notification_center/library/NotificationCenter/Gateway/Email.php

Line 164 in 068f868

\System::log(sprintf('Could not send email for message ID %s: %s', $objDraft->getMessage()->id, $e->getMessage()), __METHOD__, TL_ERROR);

Can we find a better solution for this bad error handling and user/customer experience?

[Toflar]

I don't think we can all of a sudden throw the exceptions again.

[rabauss]

That's true! Because of that I opened this issue so that it gets attention in v2 ☺️
Or maybe we can add better event in the core?

[Toflar]

NC will require a complete rewrite which will be impossible without fundings.
Core: Sure, whatever you want to work on is appreciated :)

[rabauss]

Some ideas up for discussion:

• we add a new MailErrorEvent to the core
• the MailErrorEvent can be dispatched in the notification center on errors/exceptions while executing the hook processFormData
• after executing the hook processFormData there needs to be added a new listener or subscriber which handles the MailErrorEvent (I'm not sure if listener or subscriber is prefered by contao core)
• in the event handler we could redirect to a new errorJumpTo (which needs to be added to the forms)

this feature would be nice for contao 5 :-)

[fritzmg]

this feature would be nice for contao 5 :-)

Only three days left for new features ;)

[Toflar]

In version 2.0, all of this should be possible 😊 I'm thus closing it for myself so that I can keep track of all the issues. Feel free to revisit, once there's a public beta.