diff --git a/README.rst b/README.rst
index 11f5b007..00812c03 100644
--- a/README.rst
+++ b/README.rst
@@ -29,14 +29,14 @@ Anymail currently supports these ESPs:
 * **Amazon SES**
 * **Brevo** (formerly SendinBlue)
 * **MailerSend**
-* **Mailgun**
+* **Mailgun** (Sinch transactional email)
 * **Mailjet**
-* **Mandrill** (MailChimp transactional)
+* **Mandrill** (MailChimp transactional email)
 * **Postal** (self-hosted ESP)
-* **Postmark**
+* **Postmark** (ActiveCampaign transactional email)
 * **Resend**
-* **SendGrid**
-* **SparkPost**
+* **SendGrid** (Twilio transactional email)
+* **SparkPost** (Bird transactional email)
 * **Unisender Go**
 
 Anymail includes:
diff --git a/docs/esps/mailgun.rst b/docs/esps/mailgun.rst
index 4caf9ab6..5302ff68 100644
--- a/docs/esps/mailgun.rst
+++ b/docs/esps/mailgun.rst
@@ -3,7 +3,7 @@
 Mailgun
 =======
 
-Anymail integrates with the `Mailgun <https://mailgun.com>`_
+Anymail integrates with the Sinch `Mailgun <https://mailgun.com>`_
 transactional email service, using their `messages REST API`_.
 
 .. note::
diff --git a/docs/esps/postmark.rst b/docs/esps/postmark.rst
index c83567bb..23d905ec 100644
--- a/docs/esps/postmark.rst
+++ b/docs/esps/postmark.rst
@@ -3,7 +3,7 @@
 Postmark
 ========
 
-Anymail integrates with the `Postmark`_ transactional email service,
+Anymail integrates with the ActiveCampaign `Postmark`_ transactional email service,
 using their `HTTP email API`_.
 
 .. sidebar:: Alternatives
diff --git a/docs/esps/sendgrid.rst b/docs/esps/sendgrid.rst
index 8424004e..f3ae82de 100644
--- a/docs/esps/sendgrid.rst
+++ b/docs/esps/sendgrid.rst
@@ -3,7 +3,7 @@
 SendGrid
 ========
 
-Anymail integrates with the `SendGrid`_ email service, using their `Web API v3`_.
+Anymail integrates with the Twilio `SendGrid`_ email service, using their `Web API v3`_.
 
 .. important::
 
diff --git a/docs/esps/sparkpost.rst b/docs/esps/sparkpost.rst
index c0ce6658..d03bdc2a 100644
--- a/docs/esps/sparkpost.rst
+++ b/docs/esps/sparkpost.rst
@@ -3,7 +3,7 @@
 SparkPost
 =========
 
-Anymail integrates with the `SparkPost`_ email service, using their
+Anymail integrates with the Bird `SparkPost`_ email service, using their
 `Transmissions API`_.
 
 .. versionchanged:: 8.0