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 http://sitereview.cloud.zyxel.com/, 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
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.)