diff --git a/app/lib/activitypub/activity/create.rb b/app/lib/activitypub/activity/create.rb
index 09a8caf1f..928803cd6 100644
--- a/app/lib/activitypub/activity/create.rb
+++ b/app/lib/activitypub/activity/create.rb
@@ -42,6 +42,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   def process_status
     @tags                 = []
     @mentions             = []
+    @unresolved_mentions  = []
     @silenced_account_ids = []
     @params               = {}
 
@@ -55,6 +56,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     end
 
     resolve_thread(@status)
+    resolve_unresolved_mentions(@status)
     fetch_replies(@status)
     distribute
     forward_for_reply
@@ -197,6 +199,8 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     return if account.nil?
 
     @mentions << Mention.new(account: account, silent: false)
+  rescue Mastodon::UnexpectedResponseError, HTTP::TimeoutError, HTTP::ConnectionError, OpenSSL::SSL::SSLError
+    @unresolved_mentions << tag['href']
   end
 
   def process_emoji(tag)
@@ -301,6 +305,12 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     ThreadResolveWorker.perform_async(status.id, in_reply_to_uri, { 'request_id' => @options[:request_id] })
   end
 
+  def resolve_unresolved_mentions(status)
+    @unresolved_mentions.uniq.each do |uri|
+      MentionResolveWorker.perform_in(rand(30...600).seconds, status.id, uri, { 'request_id' => @options[:request_id] })
+    end
+  end
+
   def fetch_replies(status)
     collection = @object['replies']
     return if collection.blank?
diff --git a/app/workers/mention_resolve_worker.rb b/app/workers/mention_resolve_worker.rb
new file mode 100644
index 000000000..72dcd9633
--- /dev/null
+++ b/app/workers/mention_resolve_worker.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class MentionResolveWorker
+  include Sidekiq::Worker
+  include ExponentialBackoff
+  include JsonLdHelper
+
+  sidekiq_options queue: 'pull', retry: 7
+
+  def perform(status_id, uri, options = {})
+    status = Status.find_by(id: status_id)
+    return if status.nil?
+
+    account = account_from_uri(uri)
+    account = ActivityPub::FetchRemoteAccountService.new.call(uri, request_id: options[:request_id]) if account.nil?
+
+    return if account.nil?
+
+    status.mentions.create!(account: account, silent: false)
+  rescue ActiveRecord::RecordNotFound
+    # Do nothing
+  rescue Mastodon::UnexpectedResponseError => e
+    response = e.response
+
+    if response_error_unsalvageable?(response)
+      # Give up
+    else
+      raise e
+    end
+  end
+
+  private
+
+  def account_from_uri(uri)
+    ActivityPub::TagManager.instance.uri_to_resource(uri, Account)
+  end
+end
diff --git a/spec/lib/activitypub/activity/create_spec.rb b/spec/lib/activitypub/activity/create_spec.rb
index 0986ae171..bdc8fd9d5 100644
--- a/spec/lib/activitypub/activity/create_spec.rb
+++ b/spec/lib/activitypub/activity/create_spec.rb
@@ -63,6 +63,24 @@ RSpec.describe ActivityPub::Activity::Create do
       }
     end
 
+    let(:invalid_mention_json) do
+      {
+        id: [ActivityPub::TagManager.instance.uri_for(sender), 'post2'].join('/'),
+        type: 'Note',
+        to: [
+          'https://www.w3.org/ns/activitystreams#Public',
+          ActivityPub::TagManager.instance.uri_for(follower),
+        ],
+        content: '@bob lorem ipsum',
+        published: 1.hour.ago.utc.iso8601,
+        updated: 1.hour.ago.utc.iso8601,
+        tag: {
+          type: 'Mention',
+          href: 'http://notexisting.dontexistingtld/actor',
+        },
+      }
+    end
+
     def activity_for_object(json)
       {
         '@context': 'https://www.w3.org/ns/activitystreams',
@@ -117,6 +135,25 @@ RSpec.describe ActivityPub::Activity::Create do
       # Creates two notifications
       expect(Notification.count).to eq 2
     end
+
+    it 'ignores unprocessable mention', :aggregate_failures do
+      stub_request(:get, invalid_mention_json[:tag][:href]).to_raise(HTTP::ConnectionError)
+      # When receiving the post that contains an invalid mention…
+      described_class.new(activity_for_object(invalid_mention_json), sender, delivery: true).perform
+
+      # NOTE: Refering explicitly to the workers is a bit awkward
+      DistributionWorker.drain
+      FeedInsertWorker.drain
+
+      # …it creates a status
+      status = Status.find_by(uri: invalid_mention_json[:id])
+
+      # Check the process did not crash
+      expect(status.nil?).to be false
+
+      # It has queued a mention resolve job
+      expect(MentionResolveWorker).to have_enqueued_sidekiq_job(status.id, invalid_mention_json[:tag][:href], anything)
+    end
   end
 
   describe '#perform' do
diff --git a/spec/workers/mention_resolve_worker_spec.rb b/spec/workers/mention_resolve_worker_spec.rb
new file mode 100644
index 000000000..5e23876b4
--- /dev/null
+++ b/spec/workers/mention_resolve_worker_spec.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe MentionResolveWorker do
+  let(:status_id) { -42 }
+  let(:uri) { 'https://example.com/users/unknown' }
+
+  describe '#perform' do
+    subject { described_class.new.perform(status_id, uri, {}) }
+
+    context 'with a non-existent status' do
+      it 'returns nil' do
+        expect(subject).to be_nil
+      end
+    end
+
+    context 'with a valid user' do
+      let(:status) { Fabricate(:status) }
+      let(:status_id) { status.id }
+
+      let(:service_double) { instance_double(ActivityPub::FetchRemoteAccountService) }
+
+      before do
+        allow(ActivityPub::FetchRemoteAccountService).to receive(:new).and_return(service_double)
+
+        allow(service_double).to receive(:call).with(uri, anything) { Fabricate(:account, domain: 'example.com', uri: uri) }
+      end
+
+      it 'resolves the account and adds a new mention', :aggregate_failures do
+        expect { subject }
+          .to change { status.reload.mentions }.from([]).to(a_collection_including(having_attributes(account: having_attributes(uri: uri), silent: false)))
+
+        expect(service_double).to have_received(:call).once
+      end
+    end
+  end
+end