diff --git a/src/main.rs b/src/main.rs
index 7ff67b41..fc3ab79f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 #![allow(clippy::too_many_arguments)]
-#![feature(decl_macro, proc_macro_hygiene, try_trait)]
+#![feature(decl_macro, proc_macro_hygiene, checked_duration_since, try_trait)]
 
 extern crate activitypub;
 extern crate askama_escape;
@@ -53,9 +53,10 @@ use plume_models::{
 use rocket::{fairing::AdHoc, http::ext::IntoOwned, http::uri::Origin};
 use rocket_csrf::CsrfFairingBuilder;
 use scheduled_thread_pool::ScheduledThreadPool;
+use std::collections::HashMap;
 use std::process::exit;
 use std::sync::{Arc, Mutex};
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 init_i18n!(
     "plume", ar, bg, ca, cs, de, en, eo, es, fr, gl, hi, hr, it, ja, nb, pl, pt, ro, ru, sr, sk, sv
@@ -196,6 +197,7 @@ Then try to restart Plume
         }
     });
 
+    let mut valid_domains: HashMap<&str, Instant> = HashMap::new();
     let rocket = rocket::custom(CONFIG.rocket.clone().unwrap())
         .mount(
             "/custom_domains/",
@@ -322,6 +324,7 @@ Then try to restart Plume
         .manage(dbpool)
         .manage(Arc::new(workpool))
         .manage(searcher)
+        .manage(valid_domains)
         .manage(include_i18n!())
         .attach(
             CsrfFairingBuilder::new()
diff --git a/src/routes/blogs.rs b/src/routes/blogs.rs
index 8837640a..76736b34 100644
--- a/src/routes/blogs.rs
+++ b/src/routes/blogs.rs
@@ -5,8 +5,10 @@ use rocket::{
     http::ContentType,
     request::LenientForm,
     response::{content::Content, Flash, Redirect},
+    State,
 };
 use rocket_i18n::I18n;
+use std::time::Instant;
 use std::{borrow::Cow, collections::HashMap};
 use validator::{Validate, ValidationError, ValidationErrors};
 
@@ -96,8 +98,27 @@ pub fn new(rockets: PlumeRocket, _user: User) -> Ructe {
 }
 
 #[get("/validate/<validation_id>")]
-pub fn validate(validation_id: String, rockets: PlumeRocket) -> Result {
-    unimplemented!("No idea what to do here yet")
+pub fn domain_validation(
+    validation_id: String,
+    valid_domains: State<HashMap<&str, Instant>>,
+) -> Result<String, String> {
+    let value = valid_domains.inner().get(validation_id.as_str());
+    if value.is_none() {
+        return Err(String::from("404"));
+    }
+
+    // we have valid id, now check the time
+    let valid_until = value.unwrap();
+    let now = Instant::now();
+
+    // nope, expired (410: gone)
+    if now.checked_duration_since(*valid_until).unwrap().as_secs() > 0 {
+        valid_domains.inner().remove(validation_id.as_str());
+        return Err(String::from("410"));
+    }
+
+    valid_domains.inner().remove(validation_id.as_str());
+    return Ok(String::from("200"));
 }
 
 pub mod custom {