diff --git a/addons/google_gmail/i18n/google_gmail.pot b/addons/google_gmail/i18n/google_gmail.pot
index 91eed151227c33bfea2b3a74d34534cab741c634..c2d363dce495366fb29bd1e5abe28ddb601a28c3 100644
--- a/addons/google_gmail/i18n/google_gmail.pot
+++ b/addons/google_gmail/i18n/google_gmail.pot
@@ -146,6 +146,15 @@ msgstr ""
 msgid "Please configure your Gmail credentials."
 msgstr ""
 
+#. module: google_gmail
+#: code:addons/google_gmail/models/google_gmail_mixin.py:0
+#, python-format
+msgid ""
+"Please fill the \"Username\" field with your Gmail username (your email "
+"address). This should be the same account as the one used for the Gmail "
+"OAuthentication Token."
+msgstr ""
+
 #. module: google_gmail
 #: model:ir.model.fields,field_description:google_gmail.field_google_gmail_mixin__google_gmail_refresh_token
 #: model:ir.model.fields,field_description:google_gmail.field_ir_mail_server__google_gmail_refresh_token
diff --git a/addons/google_gmail/models/google_gmail_mixin.py b/addons/google_gmail/models/google_gmail_mixin.py
index 289a0443fb81f89743193d4346c416d80e6ad553..7254c915f1d14f5cb198a14559affae959de716e 100644
--- a/addons/google_gmail/models/google_gmail_mixin.py
+++ b/addons/google_gmail/models/google_gmail_mixin.py
@@ -72,6 +72,11 @@ class GoogleGmailMixin(models.AbstractModel):
         if not self.google_gmail_uri:
             raise UserError(_('Please configure your Gmail credentials.'))
 
+        if not self.smtp_user:
+            raise UserError(_(
+                        'Please fill the "Username" field with your Gmail username (your email address). '
+                        'This should be the same account as the one used for the Gmail OAuthentication Token.'))
+
         return {
             'type': 'ir.actions.act_url',
             'url': self.google_gmail_uri,
diff --git a/addons/microsoft_outlook/i18n/microsoft_outlook.pot b/addons/microsoft_outlook/i18n/microsoft_outlook.pot
index 53723838672aa3e46be560eecc3bb7ba4181e090..021331bccfd7030fc43a02fc3e9cfe923440a863 100644
--- a/addons/microsoft_outlook/i18n/microsoft_outlook.pot
+++ b/addons/microsoft_outlook/i18n/microsoft_outlook.pot
@@ -149,6 +149,15 @@ msgstr ""
 msgid "Please configure your Outlook credentials."
 msgstr ""
 
+#. module: microsoft_outlook
+#: code:addons/microsoft_outlook/models/microsoft_outlook_mixin.py:0
+#, python-format
+msgid ""
+"Please fill the \"Username\" field with your Outlook/Office365 username "
+"(your email address). This should be the same account as the one used for "
+"the Outlook OAuthentication Token."
+msgstr ""
+
 #. module: microsoft_outlook
 #: code:addons/microsoft_outlook/models/ir_mail_server.py:0
 #, python-format
diff --git a/addons/microsoft_outlook/models/microsoft_outlook_mixin.py b/addons/microsoft_outlook/models/microsoft_outlook_mixin.py
index 2bd78018be0cfe34b2db50b1f11dada8d74785f7..abd331ff208f839e92205a57a6be391c81102478 100644
--- a/addons/microsoft_outlook/models/microsoft_outlook_mixin.py
+++ b/addons/microsoft_outlook/models/microsoft_outlook_mixin.py
@@ -81,6 +81,11 @@ class MicrosoftOutlookMixin(models.AbstractModel):
         if not self.use_microsoft_outlook_service or not self.is_microsoft_outlook_configured:
             raise UserError(_('Please configure your Outlook credentials.'))
 
+        if not self.smtp_user:
+            raise UserError(_(
+                        'Please fill the "Username" field with your Outlook/Office365 username (your email address). '
+                        'This should be the same account as the one used for the Outlook OAuthentication Token.'))
+
         return {
             'type': 'ir.actions.act_url',
             'url': self.microsoft_outlook_uri,