diff --git a/src/mailstore/filesystem.rs b/src/mailstore/filesystem.rs
index 1d2e133..b982042 100644
--- a/src/mailstore/filesystem.rs
+++ b/src/mailstore/filesystem.rs
@@ -1,11 +1,12 @@
-use crate::message::Parser as MessageParser;
-
-use super::*;
-use std::{
-    fs::{self, File},
-    io::{self, Write},
-    os::unix::fs::DirBuilderExt,
-    path::PathBuf,
+use {
+    super::*,
+    crate::{message::Parser as MessageParser, prelude::ParseMailboxError},
+    std::{
+        fs::{self, File},
+        io::{self, BufWriter, Write},
+        os::unix::fs::DirBuilderExt,
+        path::PathBuf,
+    },
 };
 
 pub trait MultiDomain: MailStore {
@@ -28,7 +29,38 @@ impl MailStore for Filesystem {
     type Error = io::Error;
 
     fn users(&self) -> Vec<Mailuser> {
-        todo!()
+        let mut users = vec![];
+        let Ok(domains) = fs::read_dir(&self.path) else {
+            return users;
+        };
+        for d in domains {
+            let Ok(dom) = d else {
+                continue;
+            };
+            let name = dom.file_name().to_string_lossy().to_string();
+            let Ok(host) = name.parse::<Host>() else {
+                continue;
+            };
+            let dom_path = dom.path();
+            let Ok(dom_users) = fs::read_dir(&dom_path) else {
+                continue;
+            };
+            for u in dom_users {
+                let Ok(user) = u else {
+                    continue;
+                };
+                if let Ok(ft) = user.file_type() {
+                    if ft.is_dir() {
+                        let username = user.file_name().to_string_lossy().to_string();
+                        users.push(Mailuser {
+                            username,
+                            host: host.clone(),
+                        });
+                    }
+                }
+            }
+        }
+        users
     }
 
     fn serves_domain(&self, domain: &str) -> bool {
@@ -143,11 +175,41 @@ impl MailStore for Filesystem {
     }
 
     fn add_user(&mut self, user: &str) -> Result<(), Self::Error> {
-        todo!()
+        let mb: Mailbox = user
+            .parse()
+            .map_err(|e: ParseMailboxError| io::Error::new(io::ErrorKind::Other, e.to_string()))?;
+        let mut path = self.path.clone();
+        path.push(&mb.host.to_string());
+        path.push(&mb.username);
+        path.push("Inbox");
+        fs::create_dir_all(&path)?;
+        if let Some(ref blurb) = mb.blurb {
+            let _last = path.pop();
+            path.push("blurb");
+            let fd = File::options()
+                .create(true)
+                .write(true)
+                .truncate(true)
+                .open(path)?;
+            let mut writer = BufWriter::new(fd);
+            writer.write_all(blurb.as_bytes())?;
+        }
+        Ok(())
     }
 
     fn remove_user(&mut self, user: &str) -> bool {
-        todo!()
+        let Ok(mu) = user.parse::<Mailbox>() else {
+            return false;
+        };
+        let mut path = self.path.clone();
+        path.push(&mu.host.to_string());
+        path.push(&mu.username);
+        if path.exists() {
+            if fs::remove_dir_all(path).is_ok() {
+                return true;
+            }
+        }
+        false
     }
 }
 
diff --git a/src/mailstore/mod.rs b/src/mailstore/mod.rs
index e167f79..b7febb6 100644
--- a/src/mailstore/mod.rs
+++ b/src/mailstore/mod.rs
@@ -144,10 +144,31 @@ impl MailStore for Domain {
         folder: &str,
         message: Message,
     ) -> Result<(), Self::Error> {
-        todo!()
+        let user = self
+            .users
+            .get_mut(user)
+            .ok_or(io::Error::new(io::ErrorKind::Other, "No such user"))?;
+        let folder = match user.folders.get_mut(folder) {
+            Some(f) => f,
+            _ => {
+                let f = Folder {
+                    name: folder.to_string(),
+                    messages: HashMap::new(),
+                };
+                user.folders.insert(folder.to_string(), f);
+                user.folders.get_mut(folder).unwrap()
+            }
+        };
+        folder.messages.insert(message.id.clone(), message);
+        Ok(())
     }
 
     fn delete_message(&mut self, user: &str, folder: &str, id: &str) -> Result<(), Self::Error> {
-        todo!()
+        if let Some(user) = self.users.get_mut(user) {
+            if let Some(folder) = user.folders.get_mut(folder) {
+                let _msg = folder.messages.remove(id);
+            }
+        }
+        Ok(())
     }
 }
diff --git a/src/time/mod.rs b/src/time/mod.rs
index f6d7ff3..3edd7c3 100644
--- a/src/time/mod.rs
+++ b/src/time/mod.rs
@@ -18,6 +18,10 @@ fn is_leap(year: i64) -> bool {
     year % 4 == 0 && (year % 100 != 0 || year % 16 == 0)
 }
 
+/// Returns the number of days in a given month. If the
+/// given month is February, then we also need to know
+/// whether it is a leap year or not, hence this function
+/// takes the year as an argument as well.
 pub fn days_in_month(month: u8, year: i64) -> i64 {
     assert!(month < 13);
     match month {