SharePoint: Most Incoming E-Mail Settings for a list are missing

Problem

When attempting to configure incoming e-mail settings of SharePoint 2013/2016 on-premises site, the list specific settings only allow enabling the incoming e-mail, and the e-mail address, but not the other options, such as what to do with the attachments.

Below picture is in Finnish, but you will see there are only these two settings, and nothing else.

Thoughts

You’ve probably gone through all settings related to incoming email, and mails are in fact arriving to the Drop folder of the SMTP Server on the SharePoint server and are probably even being processed as the emails disappear from the Drop folder.

Solution

You have custom SPEmailEventReceiver registered (via Site feature) on the site you’re on. In this scenario, the Incoming E-Mail Settings of a list will not allow you to configure further settings related to incoming emails.

It does make sense, as it is the custom event receiver handling the emails, so it would make little sense attempting to configure anything more on a single list as it would have no effect. It would of course be nice if the settings page would indicate why the settings are missing.