diff --git a/addons/mail/static/src/components/message/message.js b/addons/mail/static/src/components/message/message.js
index 5b48beaa63d..4f335ede230 100644
--- a/addons/mail/static/src/components/message/message.js
+++ b/addons/mail/static/src/components/message/message.js
@@ -87,27 +87,6 @@ export class Message extends Component {
     // Public
     //--------------------------------------------------------------------------
 
-    /**
-     * @returns {string}
-     */
-    get avatar() {
-        if (this.messageView.message.author && (!this.messageView.message.originThread || this.messageView.message.originThread.model !== 'mail.channel')) {
-            // TODO FIXME for public user this might not be accessible. task-2223236
-            // we should probably use the correspondig attachment id + access token
-            // or create a dedicated route to get message image, checking the access right of the message
-            return this.messageView.message.author.avatarUrl;
-        } else if (this.messageView.message.author && this.messageView.message.originThread && this.messageView.message.originThread.model === 'mail.channel') {
-            return `/mail/channel/${this.messageView.message.originThread.id}/partner/${this.messageView.message.author.id}/avatar_128`;
-        } else if (this.messageView.message.guestAuthor && (!this.messageView.message.originThread || this.messageView.message.originThread.model !== 'mail.channel')) {
-            return this.messageView.message.guestAuthor.avatarUrl;
-        } else if (this.messageView.message.guestAuthor && this.messageView.message.originThread && this.messageView.message.originThread.model === 'mail.channel') {
-            return `/mail/channel/${this.messageView.message.originThread.id}/guest/${this.messageView.message.guestAuthor.id}/avatar_128?unique=${this.messageView.message.guestAuthor.name}`;
-        } else if (this.messageView.message.message_type === 'email') {
-            return '/mail/static/src/img/email_icon.png';
-        }
-        return '/mail/static/src/img/smiley/avatar.jpg';
-    }
-
     /**
      * Get the date time of the message at current user locale time.
      *
diff --git a/addons/mail/static/src/components/message/message.xml b/addons/mail/static/src/components/message/message.xml
index 368c6faddea..4e9636655a6 100644
--- a/addons/mail/static/src/components/message/message.xml
+++ b/addons/mail/static/src/components/message/message.xml
@@ -29,7 +29,7 @@
                     <div class="o_Message_sidebar" t-att-class="{ 'o-message-squashed align-items-start': messageView.isSquashed }">
                         <t t-if="!messageView.isSquashed">
                             <div class="o_Message_authorAvatarContainer o_Message_sidebarItem">
-                                <img class="o_Message_authorAvatar rounded-circle" t-att-class="{ o_Message_authorRedirect: hasAuthorOpenChat, o_redirect: hasAuthorOpenChat }" t-att-src="avatar" t-on-click="_onClickAuthorAvatar" t-att-title="hasAuthorOpenChat ? OPEN_CHAT : ''" alt="Avatar"/>
+                                <img class="o_Message_authorAvatar rounded-circle" t-att-class="{ o_Message_authorRedirect: hasAuthorOpenChat, o_redirect: hasAuthorOpenChat }" t-att-src="messageView.message.avatarUrl" t-on-click="_onClickAuthorAvatar" t-att-title="hasAuthorOpenChat ? OPEN_CHAT : ''" alt="Avatar"/>
                                 <t t-if="messageView.message.author and messageView.message.author.im_status">
                                     <PartnerImStatusIcon
                                         className="'o_Message_partnerImStatusIcon'"
diff --git a/addons/mail/static/src/models/message.js b/addons/mail/static/src/models/message.js
index be9d010037a..88fb58ef468 100644
--- a/addons/mail/static/src/models/message.js
+++ b/addons/mail/static/src/models/message.js
@@ -304,6 +304,27 @@ registerModel({
             }
             return this.env._t("Anonymous");
         },
+        /**
+         * @private
+         * @returns {string}
+         */
+        _computeAvatarUrl() {
+            if (this.author && (!this.originThread || this.originThread.model !== 'mail.channel')) {
+                // TODO FIXME for public user this might not be accessible. task-2223236
+                // we should probably use the correspondig attachment id + access token
+                // or create a dedicated route to get message image, checking the access right of the message
+                return this.author.avatarUrl;
+            } else if (this.author && this.originThread && this.originThread.model === 'mail.channel') {
+                return `/mail/channel/${this.originThread.id}/partner/${this.author.id}/avatar_128`;
+            } else if (this.guestAuthor && (!this.originThread || this.originThread.model !== 'mail.channel')) {
+                return this.guestAuthor.avatarUrl;
+            } else if (this.guestAuthor && this.originThread && this.originThread.model === 'mail.channel') {
+                return `/mail/channel/${this.originThread.id}/guest/${this.guestAuthor.id}/avatar_128?unique=${this.guestAuthor.name}`;
+            } else if (this.message_type === 'email') {
+                return '/mail/static/src/img/email_icon.png';
+            }
+            return '/mail/static/src/img/smiley/avatar.jpg';
+        },
         /**
          * @returns {boolean}
          */
@@ -562,6 +583,9 @@ registerModel({
             inverse: 'messages',
         }),
         author: one('Partner'),
+        avatarUrl: attr({
+            compute: '_computeAvatarUrl'
+        }),
         /**
          * This value is meant to be returned by the server
          * (and has been sanitized before stored into db).