diff --git a/addons/im_livechat/static/tests/suggestions_tests.js b/addons/im_livechat/static/tests/suggestions_tests.js
new file mode 100644
index 00000000000..201183b662e
--- /dev/null
+++ b/addons/im_livechat/static/tests/suggestions_tests.js
@@ -0,0 +1,31 @@
+/* @odoo-module */
+
+import { Command } from "@mail/../tests/helpers/command";
+import { insertText, start, startServer } from "@mail/../tests/helpers/test_utils";
+
+QUnit.module("suggestion");
+
+QUnit.test("Suggestions are shown after delimiter was used in text (:)", async (assert) => {
+    const pyEnv = await startServer();
+    pyEnv["mail.shortcode"].create({
+        source: "hello",
+        substitution: "Hello dear customer, how may I help you?",
+    });
+    const channelId = pyEnv["discuss.channel"].create({
+        anonymous_name: "Visitor",
+        channel_type: "livechat",
+        channel_member_ids: [
+            Command.create({ partner_id: pyEnv.currentPartnerId }),
+            Command.create({ partner_id: pyEnv.publicPartnerId }),
+        ],
+    });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await insertText(".o-mail-Composer-input", ":");
+    assert.containsOnce($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", ")");
+    assert.containsNone($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", " ");
+    await insertText(".o-mail-Composer-input", ":");
+    assert.containsOnce($, ".o-mail-Composer-suggestion:contains(hello)");
+});
diff --git a/addons/mail/static/src/core/common/suggestion_hook.js b/addons/mail/static/src/core/common/suggestion_hook.js
index e4fe0ba2dd8..7b530313d1b 100644
--- a/addons/mail/static/src/core/common/suggestion_hook.js
+++ b/addons/mail/static/src/core/common/suggestion_hook.js
@@ -8,6 +8,8 @@ import { useService } from "@web/core/utils/hooks";
 export function useSuggestion() {
     const comp = useComponent();
     const sequential = useSequential();
+    let pendingFetchCount = 0;
+    /** @type {import("@mail/core/common/suggestion_service").SuggestionService} */
     const suggestionService = useService("mail.suggestion");
     const self = {
         clearRawMentions() {
@@ -38,10 +40,21 @@ export function useSuggestion() {
             if (self.search.position !== undefined && self.search.position < selectionStart) {
                 candidatePositions.push(self.search.position);
             }
-            // consider the char before the current cursor position if the
+            // consider the chars before the current cursor position if the
             // current delimiter is no longer valid (or if there is none)
-            if (selectionStart > 0) {
-                candidatePositions.push(selectionStart - 1);
+            let numberOfSpaces = 0;
+            for (let index = selectionStart - 1; index >= 0; --index) {
+                if (/\s/.test(content[index])) {
+                    numberOfSpaces++;
+                    if (numberOfSpaces === 2) {
+                        // The consideration stops after the second space since
+                        // a majority of partners have a two-word name. This
+                        // removes the need to check for mentions following a
+                        // delimiter used earlier in the content.
+                        break;
+                    }
+                }
+                candidatePositions.push(index);
             }
             const supportedDelimiters = suggestionService.getSupportedDelimiters(self.thread);
             for (const candidatePosition of candidatePositions) {
@@ -109,7 +122,7 @@ export function useSuggestion() {
             count: 0,
             items: undefined,
         }),
-        update() {
+        update({ clearSearchOnEmpty = true } = {}) {
             if (!self.search.delimiter) {
                 return;
             }
@@ -120,7 +133,11 @@ export function useSuggestion() {
             );
             const { type, mainSuggestions, extraSuggestions = [] } = suggestions;
             if (!mainSuggestions.length && !extraSuggestions.length) {
-                self.state.items = undefined;
+                if (clearSearchOnEmpty) {
+                    self.clearSearch();
+                } else {
+                    self.state.items = undefined;
+                }
                 return;
             }
             // arbitrary limit to avoid displaying too many elements at once
@@ -136,21 +153,26 @@ export function useSuggestion() {
     };
     useEffect(
         () => {
-            self.update();
+            self.update({ clearSearchOnEmpty: false });
             sequential(async () => {
                 if (self.search.position === undefined || !self.search.delimiter) {
                     return; // ignore obsolete call
                 }
-                await suggestionService.fetchSuggestions(self.search, {
-                    thread: self.thread,
-                    onFetched() {
-                        if (owl.status(comp) === "destroyed") {
-                            return;
-                        }
-                        self.update();
-                    },
-                });
-                self.update();
+                pendingFetchCount++;
+                try {
+                    await suggestionService.fetchSuggestions(self.search, {
+                        thread: self.thread,
+                        onFetched() {
+                            if (owl.status(comp) === "destroyed") {
+                                return;
+                            }
+                            self.update({ clearSearchOnEmpty: pendingFetchCount === 0 });
+                        },
+                    });
+                } finally {
+                    pendingFetchCount--;
+                }
+                self.update({ clearSearchOnEmpty: pendingFetchCount === 0 });
             });
         },
         () => {
diff --git a/addons/mail/static/tests/composer/composer_tests.js b/addons/mail/static/tests/composer/composer_tests.js
index 63eb5e0269c..318b71d820d 100644
--- a/addons/mail/static/tests/composer/composer_tests.js
+++ b/addons/mail/static/tests/composer/composer_tests.js
@@ -481,6 +481,7 @@ QUnit.test("leave command on channel", async (assert) => {
     assert.hasClass($(".o-mail-DiscussSidebarChannel:contains(general)"), "o-active");
     await insertText(".o-mail-Composer-input", "/leave");
     await afterNextRender(() => triggerHotkey("Enter"));
+    await afterNextRender(() => triggerHotkey("Enter"));
     assert.containsNone($, ".o-mail-DiscussSidebarChannel:contains(general)");
     assert.containsOnce($, ".o-mail-Discuss:contains(No conversation selected.)");
     assert.verifySteps(["You unsubscribed from general."]);
@@ -528,6 +529,7 @@ QUnit.test("leave command on chat", async (assert) => {
     assert.hasClass($(".o-mail-DiscussSidebarChannel:contains(Chuck Norris)"), "o-active");
     await insertText(".o-mail-Composer-input", "/leave");
     await afterNextRender(() => triggerHotkey("Enter"));
+    await afterNextRender(() => triggerHotkey("Enter"));
     assert.containsNone($, ".o-mail-DiscussSidebarChannel:contains(Chuck Norris)");
     assert.containsOnce($, ".o-mail-Discuss:contains(No conversation selected.)");
     assert.verifySteps(["You unpinned your conversation with Chuck Norris"]);
diff --git a/addons/mail/static/tests/discuss/core/suggestion_tests.js b/addons/mail/static/tests/discuss/core/suggestion_tests.js
index 84cb5c91cae..d4ed9a40ac5 100644
--- a/addons/mail/static/tests/discuss/core/suggestion_tests.js
+++ b/addons/mail/static/tests/discuss/core/suggestion_tests.js
@@ -133,19 +133,24 @@ QUnit.test("Sort partner suggestions by recent chats", async (assert) => {
 
 QUnit.test("suggestion are shown after deleting a character", async (assert) => {
     const pyEnv = await startServer();
+    const partnerId = pyEnv["res.partner"].create({ name: "John Doe" });
     const channelId = pyEnv["discuss.channel"].create({
         name: "General",
         channel_type: "channel",
+        channel_member_ids: [
+            Command.create({ partner_id: pyEnv.currentPartnerId }),
+            Command.create({ partner_id: partnerId }),
+        ],
     });
     const { openDiscuss } = await start();
     await openDiscuss(channelId);
-    await insertText(".o-mail-Composer-input", "/");
-    await insertText(".o-mail-Composer-input", "hee");
-    assert.containsNone($, ".o-mail-Composer-suggestion:contains(help)");
+    await insertText(".o-mail-Composer-input", "@");
+    await insertText(".o-mail-Composer-input", "John Da");
+    assert.containsNone($, ".o-mail-Composer-suggestion:contains(John Doe)");
     // Simulate pressing backspace
     await afterNextRender(() => {
         const textarea = document.querySelector(".o-mail-Composer-input");
         textarea.value = textarea.value.slice(0, -1);
     });
-    assert.containsOnce($, ".o-mail-Composer-suggestion:contains(help)");
+    assert.containsOnce($, ".o-mail-Composer-suggestion:contains(John Doe)");
 });
diff --git a/addons/mail/static/tests/suggestion/suggestion_tests.js b/addons/mail/static/tests/suggestion/suggestion_tests.js
index 9c96b525504..4939867b3b2 100644
--- a/addons/mail/static/tests/suggestion/suggestion_tests.js
+++ b/addons/mail/static/tests/suggestion/suggestion_tests.js
@@ -187,3 +187,31 @@ QUnit.test("Channel suggestions do not crash after rpc returns", async (assert)
     await deferred;
     assert.verifySteps(["get_mention_suggestions"]);
 });
+
+QUnit.test("Suggestions are shown after delimiter was used in text (@)", async (assert) => {
+    const pyEnv = await startServer();
+    const channelId = pyEnv["discuss.channel"].create({ name: "General" });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await insertText(".o-mail-Composer-input", "@");
+    assert.containsOnce($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", "NonExistingUser");
+    assert.containsNone($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", " ");
+    await insertText(".o-mail-Composer-input", "@");
+    assert.containsOnce($, ".o-mail-Composer-suggestion:contains(Mitchell Admin)");
+});
+
+QUnit.test("Suggestions are shown after delimiter was used in text (#)", async (assert) => {
+    const pyEnv = await startServer();
+    const channelId = pyEnv["discuss.channel"].create({ name: "General" });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await insertText(".o-mail-Composer-input", "#");
+    assert.containsOnce($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", "NonExistingChannel");
+    assert.containsNone($, ".o-mail-Composer-suggestion");
+    await insertText(".o-mail-Composer-input", " ");
+    await insertText(".o-mail-Composer-input", "#");
+    assert.containsOnce($, ".o-mail-Composer-suggestion:contains(General)");
+});