diff --git a/app/src/components/composer-editor/spellcheck-plugins.tsx b/app/src/components/composer-editor/spellcheck-plugins.tsx
index b6beb3e49..38425adc1 100644
--- a/app/src/components/composer-editor/spellcheck-plugins.tsx
+++ b/app/src/components/composer-editor/spellcheck-plugins.tsx
@@ -167,14 +167,6 @@ function onSpellcheckFocusedNode(editor) {
 function onSpellcheckFullDocument(editor) {
   const { value } = editor;
 
-  // re-determine the language the document is written in
-  if (value.focusBlock) {
-    const text = value.focusBlock.text;
-    if (text.length > 60) {
-      AppEnv.spellchecker.provideHintText(text.substr(text.length - 512, 512));
-    }
-  }
-
   // spellcheck all text nodes
   const texts = collectSpellcheckableTextNodes(value.document);
   const decorations = [];
diff --git a/app/src/config-schema.ts b/app/src/config-schema.ts
index 3b32ca2b2..1268e15ae 100644
--- a/app/src/config-schema.ts
+++ b/app/src/config-schema.ts
@@ -281,7 +281,7 @@ export default {
             ],
             title: localized('Spellcheck language'),
             note: localized(
-              'If you write a draft in another language, Mailspring will auto-detect it and use the correct spelling dictionary after a few sentences.'
+              'Windows and Linux only - on macOS, the spellcheck language is detected by the system as you type.'
             ),
           },
         },
diff --git a/app/src/spellchecker.ts b/app/src/spellchecker.ts
index dfac5ae72..1ddcfd746 100644
--- a/app/src/spellchecker.ts
+++ b/app/src/spellchecker.ts
@@ -1,5 +1,4 @@
-import { remote } from 'electron';
-import LRUCache from 'lru-cache';
+import { remote, webFrame } from 'electron';
 import fs from 'fs';
 import path from 'path';
 import { localized } from './intl';
@@ -7,24 +6,17 @@ import { localized } from './intl';
 const { app, MenuItem } = remote;
 const customDictFilePath = path.join(AppEnv.getConfigDirPath(), 'custom-dict.json');
 
-const { webFrame } = require('electron');
-
 class Spellchecker {
-  private _customDictLoaded = false;
-  private _saveOnLoad = false;
-  private _savingCustomDict = false;
-  private _saveAgain = false;
-  private _win;
 
-  private _customDict = {};
+  private _session = remote.getCurrentWebContents().session;
 
   constructor() {
+    //this._session = ;
 
     // Nobody will notice if spellcheck isn't available for a few seconds and it
     // takes a considerable amount of time to startup (212ms in dev mode on my 2017 MBP)
     const initHandler = () => {
-      this._win = AppEnv.getCurrentWindow();
-      this._loadCustomDict();
+      this._migrateFromCustomDict();
 
       const initialLanguage = AppEnv.config.get('core.composing.spellcheckDefaultLanguage');
       this._switchToLanguage(initialLanguage);
@@ -44,20 +36,15 @@ class Spellchecker {
 
   }
 
-  _switchToLanguage = lang => {
+  _switchToLanguage = (lang: string | undefined | null) => {
     if (lang === null || lang === undefined || lang === '') {
       lang = app.getLocale() || 'en-US';
     }
 
-    // Only switch to a language that is supported by the system.
-    // Otherwise stay at the current language. Default language is the OS language.
-    if (this._win.webContents.session.availableSpellCheckerLanguages.includes(lang)) {
-      this._win.webContents.session.setSpellCheckerLanguages([lang])
-    }
+    this._session.setSpellCheckerLanguages([lang]);
   };
 
-  _loadCustomDict = () => {
-    /*
+  _migrateFromCustomDict = () => {
     fs.readFile(customDictFilePath, (err, data) => {
       let fileData: any = data;
       if (err) {
@@ -70,78 +57,23 @@ class Spellchecker {
         }
       }
       const loadedDict = JSON.parse(fileData);
-      this._customDict = Object.assign(loadedDict, this._customDict);
-      this._customDictLoaded = true;
-      if (this._saveOnLoad) {
-        this._saveCustomDict();
-        this._saveOnLoad = false;
-      }
+      Object.keys(loadedDict).forEach(word => this._session.addWordToSpellCheckerDictionary(word));
+      fs.unlink(customDictFilePath, () => { });
     });
-    */
-  };
+  }
 
-  _saveCustomDict = () => {
-    /*
-    // If we haven't loaded the dict yet, saving could overwrite all the things.
-    // Wait until the loaded dict is merged with our working copy before saving
-    if (this._customDictLoaded) {
-      // Don't perform two writes at the same time, as this results in an overlaid
-      // version of the data. (This may or may not happen in practice, but was
-      // an issue with the tests)
-      if (this._savingCustomDict) {
-        this._saveAgain = true;
-      } else {
-        this._savingCustomDict = true;
-        fs.writeFile(customDictFilePath, JSON.stringify(this._customDict), err => {
-          if (err) {
-            AppEnv.reportError(err);
-          }
-          this._savingCustomDict = false;
-          if (this._saveAgain) {
-            this._saveAgain = false;
-            this._saveCustomDict();
-          }
-        });
-      }
-    } else {
-      this._saveOnLoad = true;
-    }
-    */
-  };
-
-  provideHintText = text => {
-    /*
-    if (!this.handler) {
-      return false;
-    }
-    this.handler.provideHintText(text);
-    */
-  };
 
   isMisspelled = (word: string) => {
-
-    if ({}.hasOwnProperty.call(this._customDict, word)) {
-      return false;
-    }
-
     return webFrame.isWordMisspelled(word)
-
   };
 
-  learnWord = word => {
-    /*
-    this._customDict[word] = '';
-    this._saveCustomDict();
-    */
+  learnWord = (word: string) => {
+    // TODO: Ensure that this work. Somehow on my Ubuntu 20.12., this does not add words to the custom dict.
+    this._session.addWordToSpellCheckerDictionary(word);
   };
 
-  unlearnWord = word => {
-    /*
-    if (word in this._customDict) {
-      delete this._customDict[word];
-      this._saveCustomDict();
-    }
-    */
+  unlearnWord = (word: string) => {
+    this._session.removeWordFromSpellCheckerDictionary(word);
   };
 
   appendSpellingItemsToMenu = async ({ menu, word, onCorrect, onDidLearn }) => {