Cyren (Zxyel) classified my fresh website as a "Spam Site". I have never hosted a mail server. What now?

Peter Dam asked:

About a month ago I bought a cheap VPS from a popular provider, and also bought a new domain name for it. It hosts Nextcloud and TT-RSS, and I have never sent an email from it — yet on, it is classified as a "Spam Site". Because of this, several corporate networks block access my site, which is quite annoying (on the internal Access Denied page, the above link is offered as a contact for reclassification requests).

There are no spam site hits on any other reputation checker sites, such as MXToolbox. I was certain that I has no malware, but nevertheless ran chrootkit and LMD, and of course nothing was found. I tried to contact Cyren several times weeks ago, through the reclassification form on the first link above, but I did not get any replies. (To be fair, I am not sure I filled the request form properly. What do "Category 1" and "Category 2" even mean?)

I thought about changing the server to get a new IP, but I think that Cyren filters based on URL, not IP (as the site is a URL checker).

What should I do so that Cyren reclassifies my site and it can be accessed again from everywhere? I am pretty much at my wit’s end about this.

(Some additional notes for context: the site uses a Let’s Encrypt SSL certificate, serves status code 500 on the front page to discourage web crawlers, and all content is on various subdomains.)

My answer:

This type of web filtering service classifies every web site they can find into one or more of several categories. Their clients then choose which categories of web sites to allow or block on their networks.

It’s likely your site was classified as "spam" due to actions of the previous owner of the domain name.

The only thing you can do is to suggest more appropriate categories for the site in the reclassification form. You won’t usually get a reply, but these reports do get reviewed and the classifications do get changed if they make sense. The catch is that, if the network from which you tried to access the site also blocks the new categories, you still won’t be able to access the site.

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