diff --git a/addons/mail/static/src/core/common/composer.xml b/addons/mail/static/src/core/common/composer.xml
index d1560c8050e..a63f9339813 100644
--- a/addons/mail/static/src/core/common/composer.xml
+++ b/addons/mail/static/src/core/common/composer.xml
@@ -102,7 +102,7 @@
 </t>
 
 <t t-name="mail.Composer.sendButton">
-    <button t-if="!compact or ui.isSmall" class="o-mail-Composer-send btn o-last border-start-0"
+    <button t-if="!compact or ui.isSmall" class="o-mail-Composer-send btn o-last"
         t-att-class="{'btn-primary': extended, 'rounded-0 rounded-end-3': !extended and !compact, 'btn-link align-self-stretch': !extended, 'border-start-0 ms-2 me-3': env.inDiscussApp}"
         t-on-click="sendMessage"
         t-att-disabled="isSendButtonDisabled"