diff --git a/PrivaPub.Tests/Http/MastodonStatusesTests.cs b/PrivaPub.Tests/Http/MastodonStatusesTests.cs
index 66bdba4..a8222f3 100644
--- a/PrivaPub.Tests/Http/MastodonStatusesTests.cs
+++ b/PrivaPub.Tests/Http/MastodonStatusesTests.cs
@@ -1,3 +1,6 @@
+using MongoDB.Entities;
+
+using PrivaPub.Models.User;
 using PrivaPub.Tests.Support;
 using PrivaPub.Tests.Support.Host;
 
@@ -385,6 +388,28 @@ namespace PrivaPub.Tests.Http
 			Assert.Equal(1, status.Number("reblogs_count"));
 		}
 
+		[Fact]
+		public async Task A_boost_reaches_the_authors_server_once_through_its_shared_inbox_and_a_like_its_own_inbox()
+		{
+			var since = DateTime.UtcNow.AddSeconds(-1);
+			var alice = await _host.Mastodon("alice");
+			var bob = new RemoteActor(_peer, "bob");
+			var remote = await _host.PublicPostFrom(bob, alice);
+			await DB.Default.Update<ForeignAvatar>().Match(f => f.ActorURI == bob.Id).Modify(f => f.SharedInboxURL, bob.SharedInbox)
+				.ExecuteAsync(TestContext.Current.CancellationToken);
+
+			(await alice.Client.Post($"/api/v1/statuses/{remote.ID}/reblog")).Ok();
+			(await alice.Client.Post($"/api/v1/statuses/{remote.ID}/unreblog")).Ok();
+			(await alice.Client.Post($"/api/v1/statuses/{remote.ID}/favourite")).Ok();
+
+			var shared = await Jobs.Deliveries(bob.SharedInbox, since, TestContext.Current.CancellationToken);
+			Assert.Single(shared, d => d.Type() == "Announce");
+			Assert.Single(shared, d => d.Type() == "Undo");
+			var own = await bob.Delivered(since);
+			Assert.DoesNotContain(own, d => d.Type() is "Announce" or "Undo");
+			Assert.Single(own, d => d.Type() == "Like");
+		}
+
 		[Fact]
 		public async Task Bookmarks_are_kept_listed_and_removed()
 		{
diff --git a/PrivaPub/Domain/Statuses/StatusService.cs b/PrivaPub/Domain/Statuses/StatusService.cs
index fb2f36e..47c8c61 100644
--- a/PrivaPub/Domain/Statuses/StatusService.cs
+++ b/PrivaPub/Domain/Statuses/StatusService.cs
@@ -487,7 +487,7 @@ namespace PrivaPub.Domain.Statuses
 				if (!original.IsFederatedCopy)
 					await Notifications.Add(original.GroupUserId, NotificationType.Reblog, me.Id, me.Uri, original.ID, token);
 				await _fanout.Distribute(reblog, token);
-				await _delivery.EnqueueToFollowers(me, announce, token, await AuthorInbox(original, token) is { } inbox ? new[] { inbox } : default);
+				await _delivery.EnqueueToFollowers(me, announce, token, await AuthorInbox(original, token, shared: true) is { } inbox ? new[] { inbox } : default);
 				return new StatusOutcome(reblog);
 			}
 
@@ -497,7 +497,7 @@ namespace PrivaPub.Domain.Statuses
 			await DB.Default.DeleteAsync<TimelineEntry>(e => e.PostId == existing.ID);
 			await DB.Default.Update<PostEntity>().MatchID(original.ID).Modify(b => b.Inc(p => p.ReblogsCount, -1)).ExecuteAsync(token);
 			await _delivery.EnqueueToFollowers(me, Undo(me, announce, $"undo-announce-{existing.ID}"), token,
-				await AuthorInbox(original, token) is { } authorInbox ? new[] { authorInbox } : default);
+				await AuthorInbox(original, token, shared: true) is { } authorInbox ? new[] { authorInbox } : default);
 			return new StatusOutcome(original);
 		}
 
@@ -595,11 +595,14 @@ namespace PrivaPub.Domain.Statuses
 			return post != default && await VisibilityPolicy.CanSee(post, me.Id, token) ? post : default;
 		}
 
-		async Task<string> AuthorInbox(PostEntity post, CancellationToken token)
+		// shared: what goes to the author's followers too (a boost) goes to its server's shared inbox, so the server gets
+		// one copy, as Mastodon sends it; two copies at once race in servers that count as they process (Misskey)
+		async Task<string> AuthorInbox(PostEntity post, CancellationToken token, bool shared = false)
 		{
 			if (!post.IsFederatedCopy || string.IsNullOrEmpty(post.AuthorAccountId))
 				return default;
-			return (await _dbEntities.ForeignAvatars.MatchID(post.AuthorAccountId).ExecuteFirstAsync(token))?.InboxURL;
+			var author = await _dbEntities.ForeignAvatars.MatchID(post.AuthorAccountId).ExecuteFirstAsync(token);
+			return shared && !string.IsNullOrEmpty(author?.SharedInboxURL) ? author.SharedInboxURL : author?.InboxURL;
 		}
 
 		async Task<bool> MayPost(Models.Group.Group group, LocalActor author, CancellationToken token)