diff --git a/core/mail_util.js b/core/mail_util.js
index 9b4bfefe..15a467ff 100644
--- a/core/mail_util.js
+++ b/core/mail_util.js
@@ -21,6 +21,7 @@ const EMAIL_REGEX =
     43:20/100.2                        { flavor : 'ftn', remote : '43:20/100.2' }
     foo@host.com                       { name : 'foo', flavor : 'email', remote : 'foo@host.com' }
     Bar <baz@foobar.net>               { name : 'Bar', flavor : 'email', remote : 'baz@foobar.com' }
+    @JoeUser@some.host.com             { name : 'Joe User', flavor : 'activitypub', remote 'JoeUser@some.host.com' }
 */
 function getAddressedToInfo(input) {
     input = input.trim();
@@ -55,6 +56,20 @@ function getAddressedToInfo(input) {
         return { name: input, flavor: Message.AddressFlavor.Local };
     }
 
+    if (firstAtPos === 0) {
+        const secondAtPos = input.indexOf('@', 1);
+        if (secondAtPos > 0) {
+            const m = input.slice(1).match(EMAIL_REGEX);
+            if (m) {
+                return {
+                    name: input.slice(1, secondAtPos),
+                    flavor: Message.AddressFlavor.ActivityPub,
+                    remote: input.slice(firstAtPos),
+                };
+            }
+        }
+    }
+
     const lessThanPos = input.indexOf('<');
     const greaterThanPos = input.indexOf('>');
     if (lessThanPos > 0 && greaterThanPos > lessThanPos) {
diff --git a/core/message.js b/core/message.js
index 6a063802..47c16821 100644
--- a/core/message.js
+++ b/core/message.js
@@ -56,6 +56,7 @@ const ADDRESS_FLAVOR = {
     Email: 'email', //  From email
     QWK: 'qwk', //  QWK packet
     NNTP: 'nntp', // NNTP article POST; often a email address
+    ActivityPub: 'activitypub', //  ActivityPub, Mastodon, etc.
 };
 
 const STATE_FLAGS0 = {
diff --git a/core/servers/content/web_handlers/activitypub.js b/core/servers/content/web_handlers/activitypub.js
index de149707..45a57b07 100644
--- a/core/servers/content/web_handlers/activitypub.js
+++ b/core/servers/content/web_handlers/activitypub.js
@@ -229,6 +229,7 @@ exports.getModule = class ActivityPubWebHandler extends WebHandlerModule {
                             return;
                         }
 
+                        //  :TODO: This stuff should probably be lifted out so it can be called ad-hoc from the queue
                         const accept = Activity.makeAccept(
                             this.webServer,
                             localActor,
@@ -281,6 +282,11 @@ exports.getModule = class ActivityPubWebHandler extends WebHandlerModule {
                                         'Unexpected status code'
                                     );
                                 }
+
+                                this.log.trace(
+                                    { inbox: actor.inbox },
+                                    'Remote server received our "Accept" successfully'
+                                );
                             }
                         );
                     });