1) Every Jabber domain is going to be a little bit different. Just visit the domain of whatever the extension after the @ symbol in his username or Google it. His current account is "YZ2Ht@jabber.calyxinstitute.org"l So you can try and visit https://kabber.calyxinstitute.org and see if there is anything there (Hint, there's not, so I had to Google "Report abuse to jabber.calyxinstitute.org" or change that out to whatever the domain he's on. It led me to the "Contact Us" page on the calyxinstitute.org, and I immediately forwarded the email he sent to abuse@calyxinstitute.org.
2) So, if you come across a domain with nothing on it, no contact info or anything, you have several options. First of all you can look up their domain name info on https://centralops.net/co/ and click "Domain Dossier". Put in the domain at the top, and check ALL the boxes "domain whois record, network whois record, traceroute and service scan". That will give you some decent info about the domain and some clues on contact info. First of all you can scroll down to I came across Once you find the Jabber domain he's using, normally there will be a page somewhere on the site that says "Contact Us", go there and if they don't have any way to report abuse, or you may just have to fill out a blank "Contact Us" form to report it, or send it via email. If the person doesn't post any contact information on their website, that's very shady and not even Twitter or any social media, you can visit.
There are a few other tricks centralops can show you. You can look at the "Creation Date" and see how long the domain has been registered for. If it was registered within the last six months, that's a bad sign. But if it says they've been registered for years, you're in a much better position. WHOIS data, which people used to use to actually enter their information, but since everyone offers a WHOIS privacy service, everybody uses that, so the best you do is maybe find their webhost, which will ALWAYS have an abuse@ contact email somewhere in the page. Worst case scenario, you can send it there. If you know what you're looking at, good for you. You can find maybe a company name they're using, what the name of their hosting company is and where it's located.
3) If you really can't find out anything else about the website. look them up in the Wayback machine: https://archive.org/web/ and sort through some of their old pages (if they have any) and see if they left any clues or anything usable. You can also use a very cool web extension called Web Archives which will search caches in ALL of these search engines caches for you & find any old hidden tucked away info they might have posted on their site and forgotten about. Web Archives (download & install) https://github.com/dessant/web-archives
"View archived and cached versions of web pages on 10+ search engines, such as the Wayback Machine, Archive.is, Google, Bing, Yandex, Gigablast, WebCite, Sogou, Memento, Naver and Yahoo Japan."
If the page isn't in English, visit https://translate.google.com and paste it and see if you can figure out what country they're in and any contact information you can Nancy Drew your way into finding. You might also need a VPN for this.
Now, you can use Google Translate to type out an email message/Jabber msg/whatever to send to them, but I recommend going into /d/CafeDread and asking if anyone is fluent in XYZ language and asking them if they'll do you a favor and have a native speaker translate your email for you. *** DON'T FORGET TO TAKE OUT ANY PERSONAL OR IDENTIFYING INFORMATION FIRST! ***
4) Last option. If you really can't find anything on the website, try a Google Site Search. To do this, just go to Google and put in he search bar "site: domain_of_website.com email" (w/o quotes) and you can change email to contact, or any other keywords you think might generate a result.
Now, some websites block search engines from accessing their site to prevent it getting indexed and everything they're doing goes out for everyone to find. You can find this out with this trick: In he search bar, type the website you're looking at and type this: http(s)://www.domain_name.com/robots.txt (The S being optional if the site uses SSL or not. When you find the robots.txt it's either going to be completely blank, have stuff in it encouraging search engines from querying and indexing the site (like an average person would want), but if you see stuff like this:
User-agent: Googlebot
Disallow: /example-subfolder/
User-agent: Bingbot
Disallow: /example-subfolder/blocked-page.html
That means they're intentionally blocking search engines from indexing their sites.
You can try alternate search engines like DuckDuckGo they might not have blocked. The command is basically the same, just reversed, so you would search "email site:domain_name.com" (w/o quotes) https://help.duckduckgo.com/duckduckgo-help-pages/results/syntax/
But DDG's search results just sucks, so you're unlikely to find much.
I had much better results with Startpage.com which uses the syntax similar to Google "site: domain_of_website.com email"(w/o quotes)
https://support.startpage.com/index.php?/Knowledgebase/Article/View/989
