diff --git a/sendgrid/helpers/mail/personalization.py b/sendgrid/helpers/mail/personalization.py
index 9239f9458..21a31c863 100644
--- a/sendgrid/helpers/mail/personalization.py
+++ b/sendgrid/helpers/mail/personalization.py
@@ -27,6 +27,20 @@ def add_email(self, email):
             self.add_bcc(email)
             return
         raise ValueError('Please use a To, Cc or Bcc object.')
+    
+    def _get_unique_recipients(self, recipients):
+        unique_recipients = []
+
+        for recipient in recipients:
+            recipient_email = recipient['email'].lower() if isinstance(recipient, dict) else recipient.email.lower()
+            if all(
+                unique_recipient['email'].lower() != recipient_email for unique_recipient in unique_recipients
+            ):
+                new_unique_recipient = recipient if isinstance(recipient, dict) else recipient.get()
+                unique_recipients.append(new_unique_recipient)
+
+        return unique_recipients
+
 
     @property
     def tos(self):
@@ -34,7 +48,7 @@ def tos(self):
 
         :rtype: list(dict)
         """
-        return self._tos
+        return self._get_unique_recipients(self._tos)
 
     @tos.setter
     def tos(self, value):
@@ -69,7 +83,7 @@ def ccs(self):
 
         :rtype: list(dict)
         """
-        return self._ccs
+        return self._get_unique_recipients(self._ccs)
 
     @ccs.setter
     def ccs(self, value):
@@ -89,7 +103,7 @@ def bccs(self):
 
         :rtype: list(dict)
         """
-        return self._bccs
+        return self._get_unique_recipients(self._bccs)
 
     @bccs.setter
     def bccs(self, value):
diff --git a/test/test_mail_helpers.py b/test/test_mail_helpers.py
index d0d09c9d3..752a9fd85 100644
--- a/test/test_mail_helpers.py
+++ b/test/test_mail_helpers.py
@@ -646,6 +646,224 @@ def test_error_is_not_raised_on_to_emails_includes_bcc_cc(self):
             html_content=HtmlContent(
                 '<strong>and easy to do anywhere, even with Python</strong>'))
 
+    def test_personalization_add_email_filters_out_duplicate_to_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_email = To('test+to0@example.com', 'Example To Name 0')
+        p.add_email(to_email)
+        p.add_email(to_email)
+
+        self.assertEqual([to_email.get()], p.tos)
+    
+    def test_personalization_add_email_filters_out_duplicate_to_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_email = To('test+to0@example.com', 'Example To Name 0')
+        to_email_with_caps = To('test+TO0@example.com', 'Example To Name 0')
+        p.add_email(to_email)
+        p.add_email(to_email_with_caps)
+
+        self.assertEqual([to_email.get()], p.tos)
+
+    def test_personalization_filters_out_duplicate_cc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_email = Cc('test+cc0@example.com', 'Example Cc Name 0')
+        p.add_email(cc_email)
+        p.add_email(cc_email)
+
+        self.assertEqual([cc_email.get()], p.ccs)
+
+    def test_personalization_filters_out_duplicate_cc_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_email = Cc('test+cc0@example.com', 'Example Cc Name 0')
+        cc_email_with_caps = Cc('test+CC0@example.com', 'Example Cc Name 0')
+        p.add_email(cc_email)
+        p.add_email(cc_email_with_caps)
+
+        self.assertEqual([cc_email.get()], p.ccs)
+
+    def test_personalization_filters_out_duplicate_bcc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_email = Bcc('test+bcc0@example.com', 'Example Bcc Name 0')
+        p.add_email(bcc_email)
+        p.add_email(bcc_email)
+
+        self.assertEqual([bcc_email.get()], p.bccs)
+
+    def test_personalization_filters_out_duplicate_bcc_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_email = Bcc('test+bcc0@example.com', 'Example Bcc Name 0')
+        bcc_email_with_caps = Bcc('test+BCC0@example.com', 'Example Bcc Name 0')
+        p.add_email(bcc_email)
+        p.add_email(bcc_email_with_caps)
+
+        self.assertEqual([bcc_email.get()], p.bccs)
+
+    def test_personalization_tos_setter_filters_out_duplicate_dict_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_emails = [{ 'email': 'test+to0@example.com', 'name': 'Example To Name 0' }] * 2
+        p.tos = to_emails
+
+        self.assertEqual([to_emails[0]], p.tos)
+
+    def test_personalization_tos_setter_filters_out_duplicate_dict_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_email = { 'email': 'test+to0@example.com', 'name': 'Example To Name 0' }
+        to_email_with_caps = { 'email': 'test+TO0@example.com', 'name': 'Example To Name 0' }
+        to_emails = [to_email, to_email_with_caps]
+        p.tos = to_emails
+
+        self.assertEqual([to_email], p.tos)
+
+    def test_personalization_tos_setter_filters_out_duplicate_to_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_emails = [To('test+to0@example.com', 'Example To Name 0')] * 2
+        p.tos = to_emails
+
+        self.assertEqual([to_emails[0].get()], p.tos)
+
+
+    def test_personalization_tos_setter_filters_out_duplicate_to_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_email = To('test+to0@example.com', 'Example To Name 0')
+        to_email_with_caps = To('test+TO0@example.com', 'Example To Name 0')
+        to_emails = [to_email, to_email_with_caps]
+        p.tos = to_emails
+
+        self.assertEqual([to_email.get()], p.tos)
+
+    def test_personalization_ccs_setter_filters_out_duplicate_dict_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_emails = [{ 'email': 'test+cc0@example.com', 'name': 'Example Cc Name 0' }] * 2
+        p.ccs = cc_emails
+
+        self.assertEqual([cc_emails[0]], p.ccs)
+
+    def test_personalization_ccs_setter_filters_out_duplicate_dict_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_email = { 'email': 'test+cc0@example.com', 'name': 'Example Cc Name 0' }
+        cc_email_with_caps = { 'email': 'test+CC0@example.com', 'name': 'Example Cc Name 0' }
+        cc_emails = [cc_email, cc_email_with_caps]
+        p.ccs = cc_emails
+
+        self.assertEqual([cc_email], p.ccs)
+
+    def test_personalization_ccs_setter_filters_out_duplicate_cc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_emails = [Cc('test+cc0@example.com', 'Example Cc Name 0')] * 2
+        p.ccs = cc_emails
+
+        self.assertEqual([cc_emails[0].get()], p.ccs)
+
+    def test_personalization_ccs_setter_filters_out_duplicate_cc_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_email = Cc('test+cc0@example.com', 'Example Cc Name 0')
+        cc_email_with_caps = Cc('test+CC0@example.com', 'Example Cc Name 0')
+        p.ccs = [cc_email, cc_email_with_caps]
+
+        self.assertEqual([cc_email.get()], p.ccs)
+
+    def test_personalization_bccs_setter_filters_out_duplicate_dict_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_emails = [{ 'email': 'test+bcc0@example.com', 'name': 'Example Bcc Name 0' }] * 2
+        p.bccs = bcc_emails
+
+        self.assertEqual([bcc_emails[0]], p.bccs)
+
+    def test_personalization_bccs_setter_filters_out_duplicate_dict_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_email = { 'email': 'test+bcc0@example.com', 'name': 'Example Bcc Name 0' }
+        bcc_email_with_caps = { 'email': 'test+BCC0@example.com', 'name': 'Example Bcc Name 0' }
+        bcc_emails = [bcc_email, bcc_email_with_caps]
+        p.bccs = bcc_emails
+
+        self.assertEqual([bcc_email], p.bccs)
+
+    def test_personalization_bccs_setter_filters_out_duplicate_bcc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_emails = [Bcc('test+bcc0@example.com', 'Example Bcc Name 0')] * 2
+        p.bccs = bcc_emails
+
+        self.assertEqual([bcc_emails[0].get()], p.bccs)
+
+    def test_personalization_bccs_setter_filters_out_duplicate_bcc_emails_ignoring_case(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_email = Bcc('test+bcc0@example.com', 'Example Bcc Name 0')
+        bcc_email_with_caps = Bcc('test+BCC0@example.com', 'Example Bcc Name 0')
+        p.bccs = [bcc_email, bcc_email_with_caps]
+
+        self.assertEqual([bcc_email.get()], p.bccs)
+
+    def test_personalization_add_to_filters_out_duplicate_to_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        to_email = To('test+to0@example.com', 'Example To Name 0')
+        p.add_to(to_email)
+        p.add_to(to_email)
+
+        expected = [to_email.get()]
+
+        self.assertEqual(expected, p.tos)
+
+    def test_personalization_add_bcc_filters_out_duplicate_bcc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        bcc_email = Bcc('test+to0@example.com', 'Example To Name 0')
+        p.add_bcc(bcc_email)
+        p.add_bcc(bcc_email)
+
+        expected = [bcc_email.get()]
+
+        self.assertEqual(expected, p.bccs)
+
+    def test_personalization_add_cc_filters_out_duplicate_cc_emails(self):
+        self.maxDiff = None
+
+        p = Personalization()
+        cc_email = Cc('test+to0@example.com', 'Example To Name 0')
+        p.add_cc(cc_email)
+        p.add_cc(cc_email)
+
+        expected = [cc_email.get()]
+
+        self.assertEqual(expected, p.ccs)
+
     def test_dynamic_template_data(self):
         self.maxDiff = None