diff --git a/odoo/addons/base/models/ir_mail_server.py b/odoo/addons/base/models/ir_mail_server.py
index 8102d2e65e7..57e856d8e66 100644
--- a/odoo/addons/base/models/ir_mail_server.py
+++ b/odoo/addons/base/models/ir_mail_server.py
@@ -277,6 +277,11 @@ class IrMailServer(models.Model):
             smtp_user = pycompat.to_native(ustr(smtp_user))
             smtp_password = pycompat.to_native(ustr(smtp_password))
             connection.login(smtp_user, smtp_password)
+
+        # Some methods of SMTP don't check whether EHLO/HELO was sent.
+        # Anyway, as it may have been sent by login(), all subsequent usages should consider this command as sent.
+        connection.ehlo_or_helo_if_needed()
+
         return connection
 
     def build_email(self, email_from, email_to, subject, body, email_cc=None, email_bcc=None, reply_to=False,