I noticed that many emails i receive from various newsletters or notifications, they have a header to automatically unsubscribe. 

See the attachment. I use the default Mail app on latest IOS.

I think it would be great to have this list unsubscribe header included in all notifications and newsletters sent from the community.

Also, i'm using Sparkpost now for regular notifications in the community. A guide to make sparkpost include these headers in emails would also be useful.

It should already be this way – at least for bulk mails. Notification mails are something different, since they don’t come from a mailing list. 

Bulk emails sent through sparkpost, a community enhancement do not include the list unsubscribe header.

Notifications may be different, but the list unsubscribe header could also be present, opting the member out of those type of notifications.

 

Just got an email because of your reply – and it had an unsubscribe header in my email app. ;-) 

And of course a link in the message to adjust my digest preferences. After all, these notifications have much more settings than just on and off. 

Then, the integration with Sparkpost is not complete. Further steps need to be made to add the list unsubscribe header.

In the sparkpost documentation, it's explained how to add it... but this still needs to update the invision board community. I did not find anything in Invision board documentation on how to set it up.

https://support.sparkpost.com/customer/portal/articles/1929894-setting-up-unsubscribe-links

Although the notifications from invision board have the 'list unsubscribe' header, the emails do not appear like in the first screenshot i attached. I cannot directly unsubscribe from emails from the default mail app on IOS

We send the header, but Sparkpost seems to interfere with it because they want it sent in their special way. It would work if using SMTP or php mail.

Even with the header sent through smtp or php mail, you can find in my post above the difference of 2 emails. From other newsletters / informal mails a message appears and i can unsubscribe directly. From invision power this does not appear.

It's not a bug, it's just a nice feature missing and probably appreciated by yahoo and gmail.

Just to chime in here - I really think there should be a one-click way to stop emails coming on all messages, whether these are notifications or bulk emails. Simple fact is that someone who posted in a recently resurrected topic who doesn't want the notifications is unlikely to take the time to remember their password, log in and sort out their notifications, and they'll end up flagging the message as spam. All we need is a 'no more emails, thanks' link at the bottom of every message, with a hash to ensure the accounts match up. 

As far as i can see this suggestion was posted in 2016 and it still does not implemented for notifications. Hope we'll see it in 4.3.x.