Last week, I accidentally discovered that Gmail is marking email sent from my domain 'andhalfafish.be'
After a bit of googling, I found out I wasn't the only one having this problem. I was just late discovering it.
Apparently, in Febuary 2016, Google introduced a new security feature in Gmail. They called it 'Making email safer for you'. This is some of the info I found on a forum :
"The big problem with e-mail has always been that it's very easy to forge a sender address. Luckily, there are some techniques to prevent this and most e-mail services and companies already use these. They allow receiving e-mail servers to check if the message is likely to really come from this sender by checking if the e-mail server that is used is the right one (SPF) and if the message is preferably digitally signed (DKIM). So you'll see this warning for some senders whose providers or companies haven't yet been implementing these techniques. This prevents Google from verifying wether these messages really came from this particular sender. - Melgior1"
So, I'm guessing this means that my web host doesn't care enough about his customers to fix this security issue for them. Or, at the very least, inform them and let them know what steps to take to fix it.
Anyway, I had no idea how to fix this, so I decided to send a tweet out into the world.
Quite unexpectedly, I received a reply from Gmail.
I can't say the suggestions they sent me were all that helpful, but in the end they steered me in the right direction : the Google Postmaster Tools.
I also mailed my web host quite a bit with questions. They were usually quick to reply, but their answers were vague and pretty much useless.
After some more research on the web, I finally managed to fix the spam warning caused by the new Google security feature.
It was actually quite easy to fix, once you knew what to do :