diff --git a/config/runtime.exs b/config/runtime.exs
index 2c434e0b..dd726029 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -6,6 +6,7 @@ import Config
 # by calling `mix release`.
 #
 # See `mix help release` for more information.
+{:ok, _} = Application.ensure_all_started(:tls_certificate_check)
 
 config :bcrypt_elixir,
   log_rounds: String.to_integer(System.get_env("BCRYPT_ROUNDS", "12"))
@@ -120,7 +121,10 @@ if config_env() == :prod do
     username: System.fetch_env!("SMTP_USERNAME"),
     password: System.fetch_env!("SMTP_PASSWORD"),
     tls: :always,
-    auth: :always
+    auth: :always,
+    tls_options:
+      [middlebox_comp_mode: false] ++
+        :tls_certificate_check.options(System.fetch_env!("SMTP_RELAY"))
 
   # Production endpoint config
   {:ok, ip} = :inet.parse_address(System.get_env("APP_IP", "127.0.0.1") |> String.to_charlist())
diff --git a/mix.exs b/mix.exs
index 515f6056..7399a2cb 100644
--- a/mix.exs
+++ b/mix.exs
@@ -65,7 +65,6 @@ defmodule Philomena.MixProject do
       {:qrcode, "~> 0.1"},
       {:redix, "~> 1.2"},
       {:bamboo, "~> 2.2"},
-      {:bamboo_smtp, "~> 4.2"},
       {:remote_ip, "~> 1.1"},
       {:briefly, "~> 0.4"},
       {:tesla, "~> 1.5"},
@@ -78,6 +77,13 @@ defmodule Philomena.MixProject do
       {:sweet_xml, "~> 0.7"},
       {:inet_cidr, "~> 1.0"},
 
+      # SMTP
+      {:tls_certificate_check, "~> 1.21"},
+      {:bamboo_smtp, "~> 4.2",
+       github: "botsquad/bamboo_smtp",
+       ref: "c630ccde40070deffc7d78ee6e4a08c9199f145b",
+       override: true},
+
       # Markdown
       {:rustler, "~> 0.27"},
 
diff --git a/mix.lock b/mix.lock
index ece08c09..f493e747 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,6 +1,6 @@
 %{
   "bamboo": {:hex, :bamboo, "2.2.0", "f10a406d2b7f5123eb1f02edfa043c259db04b47ab956041f279eaac776ef5ce", [:mix], [{:hackney, ">= 1.15.2", [hex: :hackney, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:mime, "~> 1.4", [hex: :mime, repo: "hexpm", optional: false]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "8c3b14ba7d2f40cb4be04128ed1e2aff06d91d9413d38bafb4afccffa3ade4fc"},
-  "bamboo_smtp": {:hex, :bamboo_smtp, "4.2.2", "e9f57a2300df9cb496c48751bd7668a86a2b89aa2e79ccaa34e0c46a5f64c3ae", [:mix], [{:bamboo, "~> 2.2.0", [hex: :bamboo, repo: "hexpm", optional: false]}, {:gen_smtp, "~> 1.2.0", [hex: :gen_smtp, repo: "hexpm", optional: false]}], "hexpm", "28cac2ec8adaae02aed663bf68163992891a3b44cfd7ada0bebe3e09bed7207f"},
+  "bamboo_smtp": {:git, "https://github.com/botsquad/bamboo_smtp.git", "c630ccde40070deffc7d78ee6e4a08c9199f145b", [ref: "c630ccde40070deffc7d78ee6e4a08c9199f145b"]},
   "bcrypt_elixir": {:hex, :bcrypt_elixir, "3.1.0", "0b110a9a6c619b19a7f73fa3004aa11d6e719a67e672d1633dc36b6b2290a0f7", [:make, :mix], [{:comeonin, "~> 5.3", [hex: :comeonin, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "2ad2acb5a8bc049e8d5aa267802631912bb80d5f4110a178ae7999e69dca1bf7"},
   "briefly": {:hex, :briefly, "0.4.1", "c90c0511e64bde1fe8da7e244e14acf5bc78c3f6d033db778205e1fa2feafa5c", [:mix], [], "hexpm", "fc0cafcd19c4ed0d0906ae5cf627cc6ce76b8652a160c6bde0ab9d77304ebb0a"},
   "bunt": {:hex, :bunt, "0.2.1", "e2d4792f7bc0ced7583ab54922808919518d0e57ee162901a16a1b6664ef3b14", [:mix], [], "hexpm", "a330bfb4245239787b15005e66ae6845c9cd524a288f0d141c148b02603777a5"},
@@ -33,7 +33,7 @@
   "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
   "gen_smtp": {:hex, :gen_smtp, "1.2.0", "9cfc75c72a8821588b9b9fe947ae5ab2aed95a052b81237e0928633a13276fd3", [:rebar3], [{:ranch, ">= 1.8.0", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "5ee0375680bca8f20c4d85f58c2894441443a743355430ff33a783fe03296779"},
   "gettext": {:hex, :gettext, "0.23.1", "821e619a240e6000db2fc16a574ef68b3bd7fe0167ccc264a81563cc93e67a31", [:mix], [{:expo, "~> 0.4.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "19d744a36b809d810d610b57c27b934425859d158ebd56561bc41f7eeb8795db"},
-  "hackney": {:hex, :hackney, "1.19.1", "59de4716e985dd2b5cbd4954fa1ae187e2b610a9c4520ffcb0b1653c3d6e5559", [:rebar3], [{:certifi, "~> 2.12.0", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "~> 6.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "~> 1.0.0", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~> 1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.4.1", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~> 1.1.0", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}, {:unicode_util_compat, "~> 0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "8aa08234bdefc269995c63c2282cf3cd0e36febe3a6bfab11b610572fdd1cad0"},
+  "hackney": {:hex, :hackney, "1.20.1", "8d97aec62ddddd757d128bfd1df6c5861093419f8f7a4223823537bad5d064e2", [:rebar3], [{:certifi, "~> 2.12.0", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "~> 6.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "~> 1.0.0", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~> 1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.4.1", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~> 1.1.0", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}, {:unicode_util_compat, "~> 0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "fe9094e5f1a2a2c0a7d10918fee36bfec0ec2a979994cff8cfe8058cd9af38e3"},
   "hpax": {:hex, :hpax, "0.1.2", "09a75600d9d8bbd064cdd741f21fc06fc1f4cf3d0fcc335e5aa19be1a7235c84", [:mix], [], "hexpm", "2c87843d5a23f5f16748ebe77969880e29809580efdaccd615cd3bed628a8c13"},
   "httpoison": {:hex, :httpoison, "1.8.2", "9eb9c63ae289296a544842ef816a85d881d4a31f518a0fec089aaa744beae290", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "2bb350d26972e30c96e2ca74a1aaf8293d61d0742ff17f01e0279fef11599921"},
   "hut": {:hex, :hut, "1.4.0", "7a1238ec00f95c9ec75412587ee11ac652eca308a7f4b8cc9629746d579d6cf0", [:"erlang.mk", :rebar3], [], "hexpm", "7af8704b9bae98a336f70d9560fc3c97f15665265fa603dbd05352e63d6ebb03"},
@@ -59,7 +59,7 @@
   "phoenix_slime": {:git, "https://github.com/slime-lang/phoenix_slime.git", "8944de91654d6fcf6bdcc0aed6b8647fe3398241", [ref: "8944de91654d6fcf6bdcc0aed6b8647fe3398241"]},
   "phoenix_template": {:hex, :phoenix_template, "1.0.3", "32de561eefcefa951aead30a1f94f1b5f0379bc9e340bb5c667f65f1edfa4326", [:mix], [{:phoenix_html, "~> 2.14.2 or ~> 3.0", [hex: :phoenix_html, repo: "hexpm", optional: true]}], "hexpm", "16f4b6588a4152f3cc057b9d0c0ba7e82ee23afa65543da535313ad8d25d8e2c"},
   "phoenix_view": {:hex, :phoenix_view, "2.0.2", "6bd4d2fd595ef80d33b439ede6a19326b78f0f1d8d62b9a318e3d9c1af351098", [:mix], [{:phoenix_html, "~> 2.14.2 or ~> 3.0", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:phoenix_template, "~> 1.0", [hex: :phoenix_template, repo: "hexpm", optional: false]}], "hexpm", "a929e7230ea5c7ee0e149ffcf44ce7cf7f4b6d2bfe1752dd7c084cdff152d36f"},
-  "plug": {:hex, :plug, "1.14.2", "cff7d4ec45b4ae176a227acd94a7ab536d9b37b942c8e8fa6dfc0fff98ff4d80", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "842fc50187e13cf4ac3b253d47d9474ed6c296a8732752835ce4a86acdf68d13"},
+  "plug": {:hex, :plug, "1.15.3", "712976f504418f6dff0a3e554c40d705a9bcf89a7ccef92fc6a5ef8f16a30a97", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "cc4365a3c010a56af402e0809208873d113e9c38c401cabd88027ef4f5c01fd2"},
   "plug_cowboy": {:hex, :plug_cowboy, "2.6.1", "9a3bbfceeb65eff5f39dab529e5cd79137ac36e913c02067dba3963a26efe9b2", [:mix], [{:cowboy, "~> 2.7", [hex: :cowboy, repo: "hexpm", optional: false]}, {:cowboy_telemetry, "~> 0.3", [hex: :cowboy_telemetry, repo: "hexpm", optional: false]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "de36e1a21f451a18b790f37765db198075c25875c64834bcc82d90b309eb6613"},
   "plug_crypto": {:hex, :plug_crypto, "1.2.5", "918772575e48e81e455818229bf719d4ab4181fcbf7f85b68a35620f78d89ced", [:mix], [], "hexpm", "26549a1d6345e2172eb1c233866756ae44a9609bd33ee6f99147ab3fd87fd842"},
   "poolboy": {:hex, :poolboy, "1.5.2", "392b007a1693a64540cead79830443abf5762f5d30cf50bc95cb2c1aaafa006b", [:rebar3], [], "hexpm", "dad79704ce5440f3d5a3681c8590b9dc25d1a561e8f5a9c995281012860901e3"},
@@ -80,6 +80,7 @@
   "sweet_xml": {:hex, :sweet_xml, "0.7.4", "a8b7e1ce7ecd775c7e8a65d501bc2cd933bff3a9c41ab763f5105688ef485d08", [:mix], [], "hexpm", "e7c4b0bdbf460c928234951def54fe87edf1a170f6896675443279e2dbeba167"},
   "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},
   "tesla": {:hex, :tesla, "1.7.0", "a62dda2f80d4f8a925eb7b8c5b78c461e0eb996672719fe1a63b26321a5f8b4e", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:exjsx, ">= 3.0.0", [hex: :exjsx, repo: "hexpm", optional: true]}, {:finch, "~> 0.13", [hex: :finch, repo: "hexpm", optional: true]}, {:fuse, "~> 2.4", [hex: :fuse, repo: "hexpm", optional: true]}, {:gun, "~> 1.3", [hex: :gun, repo: "hexpm", optional: true]}, {:hackney, "~> 1.6", [hex: :hackney, repo: "hexpm", optional: true]}, {:ibrowse, "4.4.0", [hex: :ibrowse, repo: "hexpm", optional: true]}, {:jason, ">= 1.0.0", [hex: :jason, repo: "hexpm", optional: true]}, {:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.0", [hex: :mint, repo: "hexpm", optional: true]}, {:msgpax, "~> 2.3", [hex: :msgpax, repo: "hexpm", optional: true]}, {:poison, ">= 1.0.0", [hex: :poison, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm", "2e64f01ebfdb026209b47bc651a0e65203fcff4ae79c11efb73c4852b00dc313"},
+  "tls_certificate_check": {:hex, :tls_certificate_check, "1.21.0", "042ab2c0c860652bc5cf69c94e3a31f96676d14682e22ec7813bd173ceff1788", [:rebar3], [{:ssl_verify_fun, "~> 1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm", "6cee6cffc35a390840d48d463541d50746a7b0e421acaadb833cfc7961e490e7"},
   "toml": {:hex, :toml, "0.7.0", "fbcd773caa937d0c7a02c301a1feea25612720ac3fa1ccb8bfd9d30d822911de", [:mix], [], "hexpm", "0690246a2478c1defd100b0c9b89b4ea280a22be9a7b313a8a058a2408a2fa70"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},
   "websock": {:hex, :websock, "0.5.3", "2f69a6ebe810328555b6fe5c831a851f485e303a7c8ce6c5f675abeb20ebdadc", [:mix], [], "hexpm", "6105453d7fac22c712ad66fab1d45abdf049868f253cf719b625151460b8b453"},