diff --git a/app/mailers/admin_mailer.rb b/app/mailers/admin_mailer.rb
index dcf0ef5c7f2..9735004c803 100644
--- a/app/mailers/admin_mailer.rb
+++ b/app/mailers/admin_mailer.rb
@@ -9,7 +9,7 @@ class AdminMailer < ApplicationMailer
   before_action :process_params
   before_action :set_instance
 
-  after_action :set_important_headers!, only: :new_critical_software_updates
+  after_action :set_important_headers!, only: [:new_critical_software_updates, :end_of_support_out_of_support_warning]
 
   around_action :set_locale
 
@@ -57,6 +57,24 @@ class AdminMailer < ApplicationMailer
     mail subject: default_i18n_subject(instance: @instance)
   end
 
+  def end_of_support_three_months_warning
+    @software_updates = SoftwareUpdate.by_version
+
+    mail subject: default_i18n_subject(instance: @instance, branch: SoftwareDeprecation.current_branch)
+  end
+
+  def end_of_support_two_weeks_warning
+    @software_updates = SoftwareUpdate.by_version
+
+    mail subject: default_i18n_subject(instance: @instance, branch: SoftwareDeprecation.current_branch)
+  end
+
+  def end_of_support_out_of_support_warning
+    @software_updates = SoftwareUpdate.by_version
+
+    mail subject: default_i18n_subject(instance: @instance, branch: SoftwareDeprecation.current_branch)
+  end
+
   def auto_close_registrations
     mail subject: default_i18n_subject(instance: @instance)
   end
diff --git a/app/models/software_deprecation.rb b/app/models/software_deprecation.rb
new file mode 100644
index 00000000000..b7f42ca20e2
--- /dev/null
+++ b/app/models/software_deprecation.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: software_deprecations
+#
+#  id             :bigint(8)        not null, primary key
+#  branch         :string           not null
+#  end_of_support :date             not null
+#  warning_issued :integer          not null
+#  created_at     :datetime         not null
+#  updated_at     :datetime         not null
+#
+class SoftwareDeprecation < ApplicationRecord
+  enum :warning_issued, {
+    none: 0,
+    three_months_warning: 1,
+    two_weeks_warning: 2,
+    out_of_support_warning: 3,
+  }, validate: true, suffix: :issued
+
+  def unsupported?
+    end_of_support.past?
+  end
+
+  def self.clear_irrelevant_branches!
+    where.not(branch: current_branch).delete_all
+  end
+
+  def self.current
+    find_by(branch: current_branch)
+  end
+
+  def self.current_branch
+    Mastodon::Version.gem_version.segments[...2].join('.')
+  end
+end
diff --git a/app/models/user_settings.rb b/app/models/user_settings.rb
index 1590ce4e89d..6e1537fdbce 100644
--- a/app/models/user_settings.rb
+++ b/app/models/user_settings.rb
@@ -54,6 +54,7 @@ class UserSettings
     setting :trends, default: true
     setting :appeal, default: true
     setting :software_updates, default: 'critical', in: %w(none critical patch all)
+    setting :end_of_support, default: true
   end
 
   namespace :interactions do
diff --git a/app/services/software_update_check_service.rb b/app/services/software_update_check_service.rb
index 353a9a6c203..c6069713006 100644
--- a/app/services/software_update_check_service.rb
+++ b/app/services/software_update_check_service.rb
@@ -3,9 +3,12 @@
 class SoftwareUpdateCheckService < BaseService
   def call
     clean_outdated_updates!
+    clean_outdated_deprecations!
     return unless SoftwareUpdate.check_enabled?
 
-    process_update_notices!(fetch_update_notices)
+    json = fetch_update_notices
+    process_update_notices!(json&.fetch('updatesAvailable', nil))
+    process_deprecation_notice!(json&.fetch('currentVersion', nil))
   end
 
   private
@@ -18,6 +21,10 @@ class SoftwareUpdateCheckService < BaseService
     end
   end
 
+  def clean_outdated_deprecations!
+    SoftwareDeprecation.clear_irrelevant_branches!
+  end
+
   def fetch_update_notices
     Request.new(:get, "#{api_url}?version=#{version}").add_headers('Accept' => 'application/json', 'User-Agent' => 'Mastodon update checker').perform do |res|
       return JSON.parse(res.body_with_limit) if res.code == 200
@@ -35,19 +42,17 @@ class SoftwareUpdateCheckService < BaseService
   end
 
   def process_update_notices!(update_notices)
-    return if update_notices.blank? || update_notices['updatesAvailable'].nil?
+    return if update_notices.blank?
 
     # Clear notices that are not listed by the update server anymore
-    SoftwareUpdate.where.not(version: update_notices['updatesAvailable'].pluck('version')).delete_all
-
-    return if update_notices['updatesAvailable'].blank?
+    SoftwareUpdate.where.not(version: update_notices.pluck('version')).delete_all
 
     # Check if any of the notices is new, and issue notifications
-    known_versions = SoftwareUpdate.where(version: update_notices['updatesAvailable'].pluck('version')).pluck(:version)
-    new_update_notices = update_notices['updatesAvailable'].filter { |notice| known_versions.exclude?(notice['version']) }
+    known_versions = SoftwareUpdate.where(version: update_notices.pluck('version')).pluck(:version)
+    new_update_notices = update_notices.filter { |notice| known_versions.exclude?(notice['version']) }
     return if new_update_notices.blank?
 
-    SoftwareUpdate.upsert_all(update_notices['updatesAvailable'].map do |notice|
+    SoftwareUpdate.upsert_all(update_notices.map do |notice|
       { version: notice['version'], urgent: notice['urgent'], type: notice['type'], release_notes: notice['releaseNotes'], end_of_support: notice['endOfSupport']&.to_date }
     end, unique_by: :version)
 
@@ -56,6 +61,18 @@ class SoftwareUpdateCheckService < BaseService
     notify_devops!(new_updates)
   end
 
+  def process_deprecation_notice!(current_version)
+    return if current_version.blank? || current_version['endOfSupport'].blank?
+
+    deprecation_notice = SoftwareDeprecation
+      .create_with(warning_issued: :none, end_of_support: current_version['endOfSupport'].to_date)
+      .find_or_create_by(branch: SoftwareDeprecation.current_branch)
+
+    deprecation_notice.update(end_of_support: current_version['endOfSupport'].to_date)
+
+    notify_of_end_of_support!(deprecation_notice)
+  end
+
   def should_notify_user?(user, urgent_version, patch_version)
     case user.settings['notification_emails.software_updates']
     when 'none'
@@ -83,4 +100,30 @@ class SoftwareUpdateCheckService < BaseService
       end
     end
   end
+
+  def should_notify_about_end_of_support?(user)
+    user.settings['notification_emails.end_of_support']
+  end
+
+  def send_notification_for_end_of_support_warning!(deprecation_notice, warning_type)
+    return if deprecation_notice.warning_issued == warning_type
+
+    User.those_who_can(:view_devops).includes(:account).find_each do |user|
+      next unless should_notify_about_end_of_support?(user)
+
+      AdminMailer.with(recipient: user.account).public_send("end_of_support_#{warning_type}").deliver_later
+    end
+
+    deprecation_notice.update!(warning_issued: warning_type)
+  end
+
+  def notify_of_end_of_support!(deprecation_notice)
+    if deprecation_notice.end_of_support.past?
+      send_notification_for_end_of_support_warning!(deprecation_notice, 'out_of_support_warning')
+    elsif deprecation_notice.end_of_support < 2.weeks.from_now
+      send_notification_for_end_of_support_warning!(deprecation_notice, 'two_weeks_warning')
+    elsif deprecation_notice.end_of_support < 3.months.from_now
+      send_notification_for_end_of_support_warning!(deprecation_notice, 'three_months_warning')
+    end
+  end
 end
diff --git a/app/views/admin/software_updates/index.html.haml b/app/views/admin/software_updates/index.html.haml
index 25de175a7be..3f117801a13 100644
--- a/app/views/admin/software_updates/index.html.haml
+++ b/app/views/admin/software_updates/index.html.haml
@@ -1,6 +1,12 @@
 - content_for :page_title do
   = t('admin.software_updates.title')
 
+- current_deprecation = SoftwareDeprecation.current
+- if current_deprecation&.unsupported?
+  .flash-message.alert= t('admin.software_updates.unsupported_branch')
+- elsif current_deprecation.present?
+  .flash-message.warning= t('admin.software_updates.nearing_eol', date: current_deprecation.end_of_support)
+
 .simple_form
   %p.lead
     = t('admin.software_updates.description')
diff --git a/app/views/admin_mailer/end_of_support_out_of_support_warning.text.erb b/app/views/admin_mailer/end_of_support_out_of_support_warning.text.erb
new file mode 100644
index 00000000000..f2cc54bae0d
--- /dev/null
+++ b/app/views/admin_mailer/end_of_support_out_of_support_warning.text.erb
@@ -0,0 +1,7 @@
+<%= raw t('admin_mailer.end_of_support_out_of_support_warning.body') %>
+
+<% @software_updates.each do |update| %>
+- Mastodon <%= update.version %>: <%= update.release_notes %>
+<% end %>
+
+<%= raw t('application_mailer.view')%> <%= admin_software_updates_url %>
diff --git a/app/views/admin_mailer/end_of_support_three_months_warning.text.erb b/app/views/admin_mailer/end_of_support_three_months_warning.text.erb
new file mode 100644
index 00000000000..bfa813e2912
--- /dev/null
+++ b/app/views/admin_mailer/end_of_support_three_months_warning.text.erb
@@ -0,0 +1,7 @@
+<%= raw t('admin_mailer.end_of_support_three_months_warning.body') %>
+
+<% @software_updates.each do |update| %>
+- Mastodon <%= update.version %>: <%= update.release_notes %>
+<% end %>
+
+<%= raw t('application_mailer.view')%> <%= admin_software_updates_url %>
diff --git a/app/views/admin_mailer/end_of_support_two_weeks_warning.text.erb b/app/views/admin_mailer/end_of_support_two_weeks_warning.text.erb
new file mode 100644
index 00000000000..6c95b018c75
--- /dev/null
+++ b/app/views/admin_mailer/end_of_support_two_weeks_warning.text.erb
@@ -0,0 +1,7 @@
+<%= raw t('admin_mailer.end_of_support_two_weeks_warning.body') %>
+
+<% @software_updates.each do |update| %>
+- Mastodon <%= update.version %>: <%= update.release_notes %>
+<% end %>
+
+<%= raw t('application_mailer.view')%> <%= admin_software_updates_url %>
diff --git a/app/views/settings/preferences/notifications/show.html.haml b/app/views/settings/preferences/notifications/show.html.haml
index fb206b13081..ac5d3335197 100644
--- a/app/views/settings/preferences/notifications/show.html.haml
+++ b/app/views/settings/preferences/notifications/show.html.haml
@@ -23,8 +23,8 @@
     .fields-group
       = ff.input :always_send_emails, wrapper: :with_label, label: I18n.t('simple_form.labels.defaults.setting_always_send_emails'), hint: I18n.t('simple_form.hints.defaults.setting_always_send_emails')
 
-    - if current_user.can?(:manage_reports, :manage_appeals, :manage_users, :manage_taxonomies) || (SoftwareUpdate.check_enabled? && current_user.can?(:view_devops))
-      %h2= t 'notifications.administration_emails'
+    - if current_user.can?(:manage_reports, :manage_appeals, :manage_users, :manage_taxonomies)
+      %h2= t 'notifications.moderation_emails'
 
       .fields-group
         = ff.input :'notification_emails.report', wrapper: :with_label, label: I18n.t('simple_form.labels.notification_emails.report') if current_user.can?(:manage_reports)
@@ -32,13 +32,21 @@
         = ff.input :'notification_emails.pending_account', wrapper: :with_label, label: I18n.t('simple_form.labels.notification_emails.pending_account') if current_user.can?(:manage_users)
         = ff.input :'notification_emails.trends', wrapper: :with_label, label: I18n.t('simple_form.labels.notification_emails.trending_tag') if current_user.can?(:manage_taxonomies)
 
-      - if SoftwareUpdate.check_enabled? && current_user.can?(:view_devops)
-        .fields-group
-          = ff.input :'notification_emails.software_updates',
-                     collection: user_settings_collection('notification_emails.software_updates'),
-                     hint: false,
-                     include_blank: false,
-                     label_method: ->(setting) { I18n.t("simple_form.labels.notification_emails.software_updates.#{setting}") },
-                     label: I18n.t('simple_form.labels.notification_emails.software_updates.label'),
-                     wrapper: :with_label,
-                     required: false
+    - if SoftwareUpdate.check_enabled? && current_user.can?(:view_devops)
+      %h2= t 'notifications.administration_emails'
+
+      .fields-group
+        = ff.input :'notification_emails.end_of_support',
+                   wrapper: :with_label,
+                   label: I18n.t('simple_form.labels.notification_emails.end_of_support'),
+                   recommended: true
+
+      .fields-group
+        = ff.input :'notification_emails.software_updates',
+                   collection: user_settings_collection('notification_emails.software_updates'),
+                   hint: false,
+                   include_blank: false,
+                   label_method: ->(setting) { I18n.t("simple_form.labels.notification_emails.software_updates.#{setting}") },
+                   label: I18n.t('simple_form.labels.notification_emails.software_updates.label'),
+                   wrapper: :with_label,
+                   required: false
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 410e54980a3..8b3aca6b68e 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -1013,6 +1013,7 @@ en:
       critical_update: Critical — please update quickly
       description: It is recommended to keep your Mastodon installation up to date to benefit from the latest fixes and features. Moreover, it is sometimes critical to update Mastodon in a timely manner to avoid security issues. For these reasons, Mastodon checks for updates every 30 minutes, and will notify you according to your email notification preferences.
       documentation_link: Learn more
+      nearing_eol: Support for the branch you are currently running will stop on %{date}, please consider updating.
       release_notes: Release notes
       supported_until: Support ends on %{date}
       title: Available updates
@@ -1021,6 +1022,7 @@ en:
         major: Major release
         minor: Minor release
         patch: Patch release — bugfixes and easy to apply changes
+      unsupported_branch: The branch you are currently running is unsupported, please update as soon as possible.
       unsupported_since: Unsupported since %{date}
       version: Version
     statuses:
@@ -1287,6 +1289,15 @@ en:
     auto_close_registrations:
       body: Due to a lack of recent moderator activity, registrations on %{instance} have been automatically switched to requiring manual review, to prevent %{instance} from being used as a platform for potential bad actors. You can switch it back to open registrations at any time.
       subject: Registrations for %{instance} have been automatically switched to requiring approval
+    end_of_support_out_of_support_warning:
+      body: The Mastodon version currently in use on your server is not supported anymore. We recommend you to update as soon as possible!
+      subject: Mastodon %{branch} used on %{instance} is now unsupported!
+    end_of_support_three_months_warning:
+      body: The Mastodon version currently in use on your server will stop being supported in 3 months. You may want to update to a newer branch ahead of time.
+      subject: Support for Mastodon %{branch} used on %{instance} to end in 3 months.
+    end_of_support_two_weeks_warning:
+      body: The Mastodon version currently in use on your server will stop being supported in 2 weeks. We recommend you update to a newer branch ahead of time.
+      subject: Support for Mastodon %{branch} used on %{instance} to end in 2 weeks.
     new_appeal:
       actions:
         delete_statuses: to delete their posts
@@ -1922,6 +1933,7 @@ en:
     administration_emails: Admin email notifications
     email_events: Events for email notifications
     email_events_hint: 'Select events that you want to receive notifications for:'
+    moderation_emails: Moderation email notifications
   number:
     human:
       decimal_units:
diff --git a/config/locales/simple_form.en.yml b/config/locales/simple_form.en.yml
index 4c9a3bce617..82c4f42bcf8 100644
--- a/config/locales/simple_form.en.yml
+++ b/config/locales/simple_form.en.yml
@@ -345,6 +345,7 @@ en:
       notification_emails:
         appeal: Someone appeals a moderator decision
         digest: Send digest e-mails
+        end_of_support: The current Mastodon version is nearing end of support
         favourite: Someone favourited your post
         follow: Someone followed you
         follow_request: Someone requested to follow you
diff --git a/config/navigation.rb b/config/navigation.rb
index dbc542bfbc6..361e06b3a4b 100644
--- a/config/navigation.rb
+++ b/config/navigation.rb
@@ -11,7 +11,7 @@ SimpleNavigation::Configuration.run do |navigation|
              SoftwareUpdate.urgent_pending? ? [material_symbol('report'), t('admin.critical_update_pending')] : [material_symbol('system_update_alt'), t('admin.update_available')]
            ),
            admin_software_updates_path,
-           html: { class: SoftwareUpdate.urgent_pending? ? 'warning' : nil },
+           html: { class: SoftwareUpdate.urgent_pending? || SoftwareDeprecation.current&.unsupported? ? 'warning' : nil },
            if: -> { Rails.configuration.x.mastodon.software_update_url.present? && current_user.can?(:view_devops) && SoftwareUpdate.pending? }
 
     n.item :profile, safe_join([material_symbol('person'), t('settings.profile')]), settings_profile_path, if: -> { current_user.functional? && !self_destruct }, highlights_on: %r{/settings/profile|/settings/featured_tags|/settings/verification}
diff --git a/db/migrate/20260706143100_create_software_deprecations.rb b/db/migrate/20260706143100_create_software_deprecations.rb
new file mode 100644
index 00000000000..d5b0780057d
--- /dev/null
+++ b/db/migrate/20260706143100_create_software_deprecations.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class CreateSoftwareDeprecations < ActiveRecord::Migration[8.1]
+  def change
+    create_table :software_deprecations do |t|
+      t.string :branch, null: false
+      t.date :end_of_support, null: false
+      t.integer :warning_issued, null: false
+
+      t.timestamps
+    end
+
+    add_index :software_deprecations, :branch, unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 1b24c81b3fe..ecf113318dc 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2026_07_06_122112) do
+ActiveRecord::Schema[8.1].define(version: 2026_07_06_143100) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
 
@@ -1157,6 +1157,15 @@ ActiveRecord::Schema[8.1].define(version: 2026_07_06_122112) do
     t.index ["var"], name: "index_site_uploads_on_var", unique: true
   end
 
+  create_table "software_deprecations", force: :cascade do |t|
+    t.string "branch", null: false
+    t.datetime "created_at", null: false
+    t.date "end_of_support", null: false
+    t.datetime "updated_at", null: false
+    t.integer "warning_issued", null: false
+    t.index ["branch"], name: "index_software_deprecations_on_branch", unique: true
+  end
+
   create_table "software_updates", force: :cascade do |t|
     t.datetime "created_at", null: false
     t.date "end_of_support"
diff --git a/spec/services/software_update_check_service_spec.rb b/spec/services/software_update_check_service_spec.rb
index ea72c52734a..d0f205e8e05 100644
--- a/spec/services/software_update_check_service_spec.rb
+++ b/spec/services/software_update_check_service_spec.rb
@@ -66,10 +66,12 @@ RSpec.describe SoftwareUpdateCheckService do
     end
 
     context 'when the server returns new versions' do
+      let(:deprecation_date) { nil }
+
       let(:server_json) do
         {
           currentVersion: {
-            endOfSupport: nil,
+            endOfSupport: deprecation_date&.iso8601,
           },
           updatesAvailable: [
             {
@@ -104,6 +106,91 @@ RSpec.describe SoftwareUpdateCheckService do
         expect { subject.call }.to change { SoftwareUpdate.pluck(:version).sort }.from(['3.5.0', '42.13.12', 'Malformed']).to(['4.2.1', '4.3.0', '5.0.0'])
       end
 
+      context 'when server returns deprecation in the distant future' do
+        let(:deprecation_date) { 5.years.from_now.to_date }
+
+        it 'updates the software deprecation info' do
+          expect { subject.call }
+            .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([]).to([[deprecation_date, 'none']])
+        end
+
+        context 'when an irrelevant deprecation was stored' do
+          before do
+            SoftwareDeprecation.create!(branch: '4.3', end_of_support: '2026-05-06'.to_date, warning_issued: :out_of_support_warning)
+          end
+
+          it 'updates the software deprecation info' do
+            expect { subject.call }
+              .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([['2026-05-06'.to_date, 'out_of_support_warning']]).to([[deprecation_date, 'none']])
+          end
+        end
+      end
+
+      context 'when server returns deprecation in 2 months' do
+        let(:deprecation_date) { 2.months.from_now.to_date }
+
+        it 'updates the software deprecation info' do
+          expect { subject.call }
+            .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([]).to([[deprecation_date, 'three_months_warning']])
+        end
+
+        context 'when an irrelevant deprecation was stored' do
+          before do
+            SoftwareDeprecation.create!(branch: '4.3', end_of_support: '2026-05-06'.to_date, warning_issued: :out_of_support_warning)
+          end
+
+          it 'updates the software deprecation info and sends email' do
+            expect { subject.call }
+              .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([['2026-05-06'.to_date, 'out_of_support_warning']]).to([[deprecation_date, 'three_months_warning']])
+              .and(have_enqueued_mail(AdminMailer, :end_of_support_three_months_warning).with(hash_including(params: { recipient: owner_user.account })).once)
+          end
+        end
+      end
+
+      context 'when server returns deprecation in 1 week' do
+        let(:deprecation_date) { 1.week.from_now.to_date }
+
+        it 'updates the software deprecation info' do
+          expect { subject.call }
+            .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([]).to([[deprecation_date, 'two_weeks_warning']])
+            .and(have_enqueued_mail(AdminMailer, :end_of_support_two_weeks_warning).with(hash_including(params: { recipient: owner_user.account })).once)
+        end
+
+        context 'when an irrelevant deprecation was stored' do
+          before do
+            SoftwareDeprecation.create!(branch: '4.3', end_of_support: '2026-05-06'.to_date, warning_issued: :out_of_support_warning)
+          end
+
+          it 'updates the software deprecation info and sends email' do
+            expect { subject.call }
+              .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([['2026-05-06'.to_date, 'out_of_support_warning']]).to([[deprecation_date, 'two_weeks_warning']])
+              .and(have_enqueued_mail(AdminMailer, :end_of_support_two_weeks_warning).with(hash_including(params: { recipient: owner_user.account })).once)
+          end
+        end
+      end
+
+      context 'when server returns deprecation in the past' do
+        let(:deprecation_date) { 1.week.ago.to_date }
+
+        it 'updates the software deprecation info' do
+          expect { subject.call }
+            .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([]).to([[deprecation_date, 'out_of_support_warning']])
+            .and(have_enqueued_mail(AdminMailer, :end_of_support_out_of_support_warning).with(hash_including(params: { recipient: owner_user.account })).once)
+        end
+
+        context 'when an irrelevant deprecation was stored' do
+          before do
+            SoftwareDeprecation.create!(branch: '4.3', end_of_support: '2026-05-06'.to_date, warning_issued: :out_of_support_warning)
+          end
+
+          it 'updates the software deprecation info and sends email' do
+            expect { subject.call }
+              .to change { SoftwareDeprecation.pluck(:end_of_support, :warning_issued) }.from([['2026-05-06'.to_date, 'out_of_support_warning']]).to([[deprecation_date, 'out_of_support_warning']])
+              .and(have_enqueued_mail(AdminMailer, :end_of_support_out_of_support_warning).with(hash_including(params: { recipient: owner_user.account })).once)
+          end
+        end
+      end
+
       context 'when no update is urgent' do
         it 'sends e-mail notifications according to settings', :aggregate_failures do
           expect { subject.call }.to have_enqueued_mail(AdminMailer, :new_software_updates)