Hi there @reyuki.
If your mail was classified as spam, there can be many reasons for this. Spamtests might be a bit misleading in some cases. But they are able to give you good general overview of the mail you created. It is especially helpful in checking the sender and potential spammy content.
In this case you seem to have not yet authenticated your domain on Brevo.
(https://help.brevo.com/hc/en-us/articles/12163873383186-Authenticate-your-domain-with-Brevo-Brevo-code-DKIM-record-DMARC-record)
If your domain was not yet authenticated at the time, then this certainly caused difficulties in sending. If this has not been done, there is a high probability that your mail will end up in spam or be rejected.
The providers also always track sending by domain, so they have an existing domain reputation that determines placement in the inbox, regardless of which platform the emails originate from. If the shared domain is used, the domain reputation is based on the totality of activity on all sending platforms.
If they have not been sending for very long, it could be that the ISPs are just treating the emails with caution because the domain has a new or neutral reputation status.
You should also always achieve good click and open rates with your recipients. This performance also affects Brevo; if the click and open rates are low, it is much more likely that the emails will be placed in non-inbox folders.
Please make sure your email lists are clean. Avoid sending to invalid or inactive email addresses as this can damage your reputation.
Content filters are no longer so common, at least with large providers such as Google or GMX. Perhaps they are filtered on the basis of a personal Bayesian filter that the owner of the mailbox has trained. (This happens quite often with test emails because they are not always opened, almost never clicked on and almost always deleted shortly afterwards. The filter then “learns” from the user’s behavior that the email was most likely unwanted).
Avoid content that could be classified as spam. Pay attention to correct formatting and avoid lurid subject lines or content.
You should register with a tool such as Google Postmaster. This is where you will find the best data to help troubleshoot if you have created a sending history. I would suggest you to review this closely and consider feedback on trends you can see there.
Subscribe to feedback loops (FBL) from email providers to know when users are marking your emails as spam.
I hope it helps. Happy sending!
