Update Jakarta Mail info in ref docs

Closes gh-29708

src/docs/asciidoc/integration.adoc

@@ -4314,14 +4314,16 @@ This section describes how to send email with the Spring Framework.
 
 .Library dependencies
 ****
-The following JAR needs to be on the classpath of your application in order to use
-the Spring Framework's email library:
+The following JAR needs to be on the classpath of your application in order to use the
+Spring Framework's email support:
 
-* The https://eclipse-ee4j.github.io/mail/[JavaMail / Jakarta Mail 1.6] library
+* The https://jakartaee.github.io/mail-api/[JavaMail / Jakarta Mail 1.6] library
 
 This library is freely available on the web -- for example, in Maven Central as
-`com.sun.mail:jakarta.mail`. Please make sure to use the latest 1.6.x version
-rather than Jakarta Mail 2.0 (which comes with a different package namespace).
+`com.sun.mail:jakarta.mail`. Please make sure to use the latest 1.6.x version (which uses
+the `javax.mail` package namespace) rather than Jakarta Mail 2.0 (which uses the
+`jakarta.mail` package namespace). See the code in the `v1.x` branch of the
+https://github.com/jakartaee/mail-api/tree/v1.x[Jakarta Mail API repository].
 ****
 
 The Spring Framework provides a helpful utility library for sending email that shields