After a long time of absence, I had made a new post in this forum.

When I went to logout afterwards, I configured email alerts for this account.

I basically entered an email address in the field that was empty at that time and unchecked a few boxes for events I was currently not interested in receiving notifications about.

However, I left check marks for "Announcements" and "Replies To My Posts" set and the delivery method to "Individual Emails".

Then I logged out.

Some time later - perhaps 2 hours, I returned to the forum and noticed, there was a reply to my post.

However, up to now, I have not noticed any email notifications in my inbox or my spam folder.

So I figured, either the email notifications are sent in a different way or schedule, then I thought, or email notifications are not working for me at the moment.

Checking the logs, I see that emails were sent to you, but were rejected by your hosting provider, GMX.

Further information:

GMX claims that messages to you were rejected due to invalid or missing DKIM signatures. https://postmaster.gmx.net/de/case?c=r0103&i=ip&v=45.33.6.223&r=1N1daa-1qxNsD44vg-00yDN6. But, similar messages were evaluated by GMail and Protonmail and found the DKIM signatures to be just fine:

Gmail:

ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@sqlite.org header.s=mail header.b=P71xlQeN;
       spf=pass (google.com: domain of noreply35b34aa0e@fossil-scm.org designates 45.33.6.223 as permitted sender) smtp.mailfrom=noreply35b34aa0e@fossil-scm.org;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=fossil-scm.org

Protonmail:

Authentication-Results: mail.protonmail.ch; dkim=pass (Good 1024 bit
    rsa-sha256 signature) header.d=sqlite.org header.a=rsa-sha256
Authentication-Results: mail.protonmail.ch; dmarc=pass (p=none dis=none)
 header.from=fossil-scm.org
Authentication-Results: mail.protonmail.ch; spf=pass smtp.mailfrom=fossil-scm.org
Authentication-Results: mail.protonmail.ch; arc=none smtp.remote-ip=45.33.6.223
Authentication-Results: mail.protonmail.ch; dkim=pass (1024-bit key) 

Methinks there is something wrong at GMX.

Checking the logs, I see that emails were sent to you, but were rejected by your hosting provider, GMX.

That is interesting/good to know.

I didn't know that could be happening.

GMX kind of always implied, it would not reject emails by it's own digression.
Hence the existence and use of a spam folder.

Also I was not informed about them doing that - except now from you.

Receiving emails from the fossil forum used to work in the past
and I do not think I have changed anything in my mailbox setup that should influence such things.

I remember another case, arguably more justified, when emails from another source did not arrive at that mailbox, that I would have wanted to arrive there - some time ago.

I consider finding another email provider, but this may perhaps not happen very soon.

If GMX does reject those emails, should I remove that address from the settings here?

Methinks there is something wrong at GMX.

I am afraid, you are right about that.

I have unchecked all topics for email notifications, that should make sure no further attempts to send email notifications should occur.

Perhaps that may contribute to calm down GMX ;)
- even if that is probably a very tiny contribution in that direction.

Most free email providers these days are not in the business of notifying their "customers" of emails that are being blocked.

GMX also did have payment schemes - I believe, they probably still have.
Therefore, I presume, they also have some users paying money to them.

If such payments would bring better mail delivery seem doubtful to me.

I did a little search for GMX rejecting emails yesterday.

I found some help pages with similar topics,
but them doing the blocking, appears to be a total "no mention"
- except for "user defined filters" perhaps.

They have that spam folder and daily spam reports, to try to make their "customers" believe,
they may still receive every email they wanted.
The contents of my spam folders these days always appears to be real spam.

Deliverability to Gmail has gone seriously downhill in the last year or two.

I never quite trusted Gmail, but I was not really aware of that.

Apparently it is better not to rely on emails these days.

Good luck finding a better provider.

Thank you Andy.