diff --git a/Cargo.lock b/Cargo.lock
index 4774abe..ea49c6f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -29,6 +29,12 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9e1b586273c5702936fe7b7d6896644d8be71e6314cfe09d3167c95f712589e8"
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
 [[package]]
 name = "block-buffer"
 version = "0.10.3"
@@ -38,6 +44,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "cc"
+version = "1.0.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50d30906286121d95be3d479533b458f87493b30a4b5f79a607db8f5d11aa91f"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -54,6 +66,43 @@ dependencies = [
  "encoding_rs",
 ]
 
+[[package]]
+name = "clap"
+version = "4.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3d7ae14b20b94cb02149ed21a86c423859cbe18dc7ed69845cace50e52b40a5"
+dependencies = [
+ "bitflags",
+ "clap_derive",
+ "clap_lex",
+ "is-terminal",
+ "once_cell",
+ "strsim",
+ "termcolor",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "44bec8e5c9d09e439c4335b1af0abaab56dcf3b94999a936e1bb47b9134288f0"
+dependencies = [
+ "heck",
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "350b9cf31731f9957399229e9b2adc51eeabdfbe9d71d9a0552275fd12710d09"
+dependencies = [
+ "os_str_bytes",
+]
+
 [[package]]
 name = "cpufeatures"
 version = "0.2.5"
@@ -143,6 +192,7 @@ name = "email"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "clap",
  "mailparse",
  "memmap",
  "rayon",
@@ -161,6 +211,27 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "errno"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f639046355ee4f37944e44f60642c6f3a7efa3cf6b78c78a0d989a8ce6c396a1"
+dependencies = [
+ "errno-dragonfly",
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "errno-dragonfly"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa68f1b12764fab894d2755d2518754e71b4fd80ecfb822714a1206c2aab39bf"
+dependencies = [
+ "cc",
+ "libc",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.6"
@@ -171,6 +242,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "heck"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
+
 [[package]]
 name = "hermit-abi"
 version = "0.2.6"
@@ -180,12 +257,46 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "hermit-abi"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fed44880c466736ef9a5c5b5facefb5ed0785676d0c02d612db14e54f0d84286"
+
+[[package]]
+name = "io-lifetimes"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1abeb7a0dd0f8181267ff8adc397075586500b81b28a73e8a0208b00fc170fb3"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "is-terminal"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21b6b32576413a8e69b90e952e4a026476040d81017b80445deda5f2d3921857"
+dependencies = [
+ "hermit-abi 0.3.1",
+ "io-lifetimes",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.139"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "201de327520df007757c1f0adce6e827fe8562fbc28bfd9c15571c66ca1f5f79"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f051f77a7c8e6957c0696eac88f26b0117e54f52d3fc682ab19397a8812846a4"
+
 [[package]]
 name = "mailparse"
 version = "0.14.0"
@@ -228,10 +339,46 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fac9e2da13b5eb447a6ce3d392f23a29d8694bff781bf03a16cd9ac8697593b"
 dependencies = [
- "hermit-abi",
+ "hermit-abi 0.2.6",
  "libc",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.17.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7e5500299e16ebb147ae15a00a942af264cf3688f47923b8fc2cd5858f23ad3"
+
+[[package]]
+name = "os_str_bytes"
+version = "6.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b7820b9daea5457c9f21c69448905d723fbd21136ccf521748f23fd49e723ee"
+
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.51"
@@ -295,6 +442,20 @@ version = "0.6.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "456c603be3e8d448b072f410900c09faf164fbce2d480456f50eea6e25f9c848"
 
+[[package]]
+name = "rustix"
+version = "0.36.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd5c6ff11fecd55b40746d1995a02f2eb375bf8c00d192d521ee09f42bef37bc"
+dependencies = [
+ "bitflags",
+ "errno",
+ "io-lifetimes",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -321,6 +482,12 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
+
 [[package]]
 name = "syn"
 version = "1.0.108"
@@ -332,6 +499,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "termcolor"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be55cf8942feac5c765c2c993422806843c9a9a45d4d5c407ad6dd2ea95eb9b6"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.38"
@@ -411,3 +587,69 @@ name = "winapi-x86_64-pc-windows-gnu"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "windows-sys"
+version = "0.45.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75283be5efb2831d37ea142365f009c02ec203cd29a3ebecbc093d52315b66d0"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e2522491fbfcd58cc84d47aeb2958948c4b8982e9a2d8a2a35bbaed431390e7"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c9864e83243fdec7fc9c5444389dcbbfd258f745e7853198f365e3c4968a608"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c8b1b673ffc16c47a9ff48570a9d85e25d265735c503681332589af6253c6c7"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de3887528ad530ba7bdbb1faa8275ec7a1155a45ffa57c37993960277145d640"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf4d1122317eddd6ff351aa852118a2418ad4214e6613a50e0191f7004372605"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1040f221285e17ebccbc2591ffdc2d44ee1f9186324dd3e84e99ac68d699c45"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "628bfdf232daa22b0d64fdb62b09fcc36bb01f05a3939e20ab73aaf9470d0463"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.42.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "447660ad36a13288b1db4d4248e857b510e8c3a225c822ba4fb748c0aafecffd"
diff --git a/Cargo.toml b/Cargo.toml
index 3798d74..3d9e62f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,6 +8,7 @@ edition = "2018"
 
 [dependencies]
 anyhow = "1.0.69"
+clap = { version = "4.1.8", features = ["derive"] }
 mailparse = "0.14.0"
 memmap = "0.7.0"
 rayon = "1.6.1"
diff --git a/src/bin/fingerprint.rs b/src/bin/fingerprint.rs
new file mode 100644
index 0000000..9102a55
--- /dev/null
+++ b/src/bin/fingerprint.rs
@@ -0,0 +1,136 @@
+use std::{
+    collections::HashMap,
+    fs::File,
+    path::Path,
+    time::{SystemTime, UNIX_EPOCH},
+};
+
+use clap::Parser;
+use email::{fingerprint, should_skip, EmailError};
+use mailparse::{dateparse, parse_mail, MailHeaderMap};
+use memmap::MmapOptions;
+use rayon::{iter::ParallelBridge, prelude::ParallelIterator};
+use walkdir::WalkDir;
+
+/// Simple program to greet a person
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    /// Number years to search through
+    #[arg(short, long, default_value_t = 1)]
+    years: usize,
+
+    /// Enable verbose logging
+    #[arg(short, long, default_value_t = false)]
+    verbose: bool,
+
+    /// Number of example filenames to print
+    #[arg(short, long, default_value_t = 1)]
+    examples: usize,
+
+    /// Show top N fingerprints
+    #[arg(short, long, default_value_t = 10)]
+    top_n: usize,
+
+    /// List of input directories to recursively search
+    input_dir: String,
+}
+
+fn main() -> anyhow::Result<()> {
+    let args = Args::parse();
+    let n = 1;
+    // Just check messages from the last N years.
+    let max_age = 60 * 60 * 24 * 365 * n;
+    let start = std::time::Instant::now();
+    let unix_secs = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("couldn't get unix time");
+    let youngest = unix_secs.as_secs() as i64 - max_age;
+    let dir = args.input_dir.clone();
+    let map = WalkDir::new(&dir)
+        .into_iter()
+        .par_bridge()
+        .filter_map(|entry| entry.ok())
+        .filter_map(|entry| {
+            if entry.file_type().is_dir() {
+                if args.verbose {
+                    println!(
+                        "{} ",
+                        entry
+                            .path()
+                            .strip_prefix(&dir)
+                            .expect("failed to strip dir")
+                            .display()
+                    );
+                }
+                return None;
+            }
+            let arg = entry.path().display().to_string();
+            if should_skip(&arg) {
+                return None;
+            }
+            match parse(&arg, youngest) {
+                Ok(Some(h)) => Some((h, arg)),
+                // Skip old emails
+                Ok(None) => return None,
+                Err(e) => {
+                    eprintln!("{}: failed {}", arg, e);
+                    None
+                }
+            }
+        })
+        .fold(
+            || HashMap::new(),
+            |mut m, (h, arg)| {
+                m.entry(h).or_insert(Vec::new()).push(arg);
+                m
+            },
+        )
+        // Merge maps created by parallel iteration.
+        .reduce(
+            || HashMap::new(),
+            |mut acc, m| {
+                for (k, v) in m {
+                    acc.entry(k).or_insert(Vec::new()).extend(v);
+                }
+                acc
+            },
+        );
+
+    let mut res: Vec<_> = map
+        .into_iter()
+        .map(|(hash, paths)| {
+            (
+                paths.len(),
+                hash,
+                paths.into_iter().take(args.examples).collect::<Vec<_>>(),
+            )
+        })
+        .collect();
+    res.sort();
+    res.reverse();
+    for (cnt, hash, ex) in res.into_iter().take(args.top_n) {
+        println!("{cnt} {}\n{hash}\n", ex.join("\n"));
+    }
+    println!("Runtime: {:.2}s", start.elapsed().as_secs_f32());
+    Ok(())
+}
+
+// If the date in the email is before youngest Ok(None) will be returned.
+fn parse<P: AsRef<Path>>(path: P, youngest: i64) -> Result<Option<String>, EmailError> {
+    let file = File::open(&path)?;
+    let mmap = unsafe { MmapOptions::new().map(&file)? };
+    let m = parse_mail(&mmap)?;
+    let d = dateparse(
+        m.headers
+            .get_first_value("Date")
+            .unwrap_or("".to_string())
+            .as_str(),
+    )
+    .unwrap_or(0);
+    if d < youngest {
+        return Ok(None);
+    }
+    //println!("{}: {:#?}", path.as_ref().display(), m.ctype);
+    Ok(Some(fingerprint(&m).join("\n")))
+}
diff --git a/src/bin/summarize.rs b/src/bin/summarize.rs
new file mode 100644
index 0000000..fc3e3ca
--- /dev/null
+++ b/src/bin/summarize.rs
@@ -0,0 +1,25 @@
+use std::fs::File;
+
+use clap::Parser;
+use email::fingerprint;
+use mailparse::parse_mail;
+use memmap::MmapOptions;
+
+/// Use library to summarize information about given mail files
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    /// List of files to summarize
+    paths: Vec<String>,
+}
+
+fn main() -> anyhow::Result<()> {
+    let args = Args::parse();
+    for path in args.paths {
+        let file = File::open(&path)?;
+        let mmap = unsafe { MmapOptions::new().map(&file)? };
+        let m = parse_mail(&mmap)?;
+        println!("{path}\n{}", fingerprint(&m).join("\n"));
+    }
+    Ok(())
+}
diff --git a/src/lib.rs b/src/lib.rs
index 7a67274..96eea49 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,6 @@
 use std::{fs::File, path::Path};
 
-use mailparse::{parse_headers, MailHeader, MailHeaderMap, MailParseError};
+use mailparse::{parse_headers, MailHeader, MailHeaderMap, MailParseError, ParsedMail};
 use memmap::MmapOptions;
 use sha1::{Digest, Sha1};
 use thiserror::Error;
@@ -44,6 +44,38 @@ pub fn hash_headers(hdrs: &[MailHeader]) -> String {
     format!("{:x}", hasher.finalize())
 }
 
+// Returns true if the last part of path is known to be a non-mail file commonly found under
+// Maildir/
+const SKIP_FILES: &[&str] = &[
+    "docdata.glass",
+    "flintlock",
+    "iamglass",
+    ".mbsyncstate",
+    "position.glass",
+    "postlist.glass",
+    "termlist.glass",
+    ".uidvalidity",
+];
+pub fn should_skip(path: &str) -> bool {
+    let filename: &str = if let Some(idx) = path.rfind("/") {
+        &path[idx + 1..]
+    } else {
+        path
+    };
+    SKIP_FILES.contains(&filename)
+}
+
+pub fn fingerprint(pm: &ParsedMail<'_>) -> Vec<String> {
+    fingerprint_rec(pm, 0)
+}
+fn fingerprint_rec(pm: &ParsedMail<'_>, depth: usize) -> Vec<String> {
+    let mut v = vec![format!("{}{}", " ".repeat(depth * 2), pm.ctype.mimetype)];
+    for c in &pm.subparts {
+        v.extend(fingerprint_rec(&c, depth + 1));
+    }
+    v
+}
+
 #[cfg(test)]
 mod tests {
     use mailparse::{parse_headers, MailHeader, MailHeaderMap};