diff --git a/roles/matrix-bridge-mautrix-facebook/defaults/main.yml b/roles/matrix-bridge-mautrix-facebook/defaults/main.yml
index e99514e0..14db76d8 100644
--- a/roles/matrix-bridge-mautrix-facebook/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-facebook/defaults/main.yml
@@ -69,6 +69,8 @@ matrix_mautrix_facebook_login_shared_secret: ''
 
 matrix_mautrix_facebook_bridge_login_shared_secret_map: "{{ {matrix_mautrix_facebook_homeserver_domain: matrix_mautrix_facebook_login_shared_secret} if matrix_mautrix_facebook_login_shared_secret else {} }}"
 
+matrix_mautrix_facebook_appservice_bot_username: facebookbot
+
 matrix_mautrix_facebook_bridge_presence: true
 
 # Default configuration template which covers the generic use case.
@@ -101,8 +103,11 @@ matrix_mautrix_facebook_registration_yaml: |
     users:
     - exclusive: true
       regex: '^@facebook_.+:{{ matrix_mautrix_facebook_homeserver_domain|regex_escape }}$'
+    - exclusive: true
+      regex: '^@{{ matrix_mautrix_facebook_appservice_bot_username|regex_escape }}:{{ matrix_mautrix_facebook_homeserver_domain|regex_escape }}$'
   url: {{ matrix_mautrix_facebook_appservice_address }}
-  sender_localpart: facebookbot
+  # See https://github.com/tulir/mautrix-signal/issues/43
+  sender_localpart: _bot_{{ matrix_mautrix_facebook_appservice_bot_username|to_json }}
   rate_limited: false
 
 matrix_mautrix_facebook_registration: "{{ matrix_mautrix_facebook_registration_yaml|from_yaml }}"
diff --git a/roles/matrix-bridge-mautrix-facebook/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-facebook/templates/config.yaml.j2
index 6fe3254d..628db713 100644
--- a/roles/matrix-bridge-mautrix-facebook/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-facebook/templates/config.yaml.j2
@@ -46,7 +46,7 @@ appservice:
     # The unique ID of this appservice.
     id: facebook
     # Username of the appservice bot.
-    bot_username: facebookbot
+    bot_username: {{ matrix_mautrix_facebook_appservice_bot_username|to_json }}
     # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
     # to leave display name/avatar as-is.
     bot_displayname: Facebook bridge bot
diff --git a/roles/matrix-bridge-mautrix-hangouts/defaults/main.yml b/roles/matrix-bridge-mautrix-hangouts/defaults/main.yml
index 8dfee030..2b13ea21 100644
--- a/roles/matrix-bridge-mautrix-hangouts/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-hangouts/defaults/main.yml
@@ -71,6 +71,8 @@ matrix_mautrix_hangouts_appservice_database: "{{
 # Can be set to enable automatic double-puppeting via Shared Secret Auth (https://github.com/devture/matrix-synapse-shared-secret-auth).
 matrix_mautrix_hangouts_login_shared_secret: ''
 
+matrix_mautrix_hangouts_appservice_bot_username: hangoutsbot
+
 # Default configuration template which covers the generic use case.
 # You can customize it by controlling the various variables inside it.
 #
@@ -101,8 +103,11 @@ matrix_mautrix_hangouts_registration_yaml: |
     users:
     - exclusive: true
       regex: '^@hangouts_.+:{{ matrix_mautrix_hangouts_homeserver_domain|regex_escape }}$'
+    - exclusive: true
+      regex: '^@{{ matrix_mautrix_hangouts_appservice_bot_username|regex_escape }}:{{ matrix_mautrix_hangouts_homeserver_domain|regex_escape }}$'
   url: {{ matrix_mautrix_hangouts_appservice_address }}
-  sender_localpart: hangoutsbot
+  # See https://github.com/tulir/mautrix-signal/issues/43
+  sender_localpart: _bot_{{ matrix_mautrix_hangouts_appservice_bot_username }}
   rate_limited: false
 
 matrix_mautrix_hangouts_registration: "{{ matrix_mautrix_hangouts_registration_yaml|from_yaml }}"
diff --git a/roles/matrix-bridge-mautrix-hangouts/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-hangouts/templates/config.yaml.j2
index cc2ca90b..7ff7d539 100644
--- a/roles/matrix-bridge-mautrix-hangouts/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-hangouts/templates/config.yaml.j2
@@ -32,7 +32,7 @@ appservice:
     # The unique ID of this appservice.
     id: hangouts
     # Username of the appservice bot.
-    bot_username: hangoutsbot
+    bot_username: {{ matrix_mautrix_hangouts_appservice_bot_username|to_json }}
     # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
     # to leave display name/avatar as-is.
     bot_displayname: Hangouts bridge bot
diff --git a/roles/matrix-bridge-mautrix-signal/defaults/main.yml b/roles/matrix-bridge-mautrix-signal/defaults/main.yml
index 65318f19..aaa0a166 100644
--- a/roles/matrix-bridge-mautrix-signal/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-signal/defaults/main.yml
@@ -43,6 +43,8 @@ matrix_mautrix_signal_daemon_systemd_wanted_services_list: []
 matrix_mautrix_signal_appservice_token: ''
 matrix_mautrix_signal_homeserver_token: ''
 
+matrix_mautrix_signal_appservice_bot_username: signalbot
+
 # Database-related configuration fields
 #
 # This bridge only supports postgres.
diff --git a/roles/matrix-bridge-mautrix-signal/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-signal/templates/config.yaml.j2
index 28fff6f0..dc2cff36 100644
--- a/roles/matrix-bridge-mautrix-signal/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-signal/templates/config.yaml.j2
@@ -43,7 +43,7 @@ appservice:
     # The unique ID of this appservice.
     id: signal
     # Username of the appservice bot.
-    bot_username: signalbot
+    bot_username: {{ matrix_mautrix_signal_appservice_bot_username|to_json }}
     # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
     # to leave display name/avatar as-is.
     bot_displayname: Signal bridge bot
diff --git a/roles/matrix-bridge-mautrix-signal/templates/registration.yaml.j2 b/roles/matrix-bridge-mautrix-signal/templates/registration.yaml.j2
index 45cc5a0f..db486b9c 100644
--- a/roles/matrix-bridge-mautrix-signal/templates/registration.yaml.j2
+++ b/roles/matrix-bridge-mautrix-signal/templates/registration.yaml.j2
@@ -6,9 +6,12 @@ namespaces:
     users:
     - exclusive: true
       regex: '^@signal_.+:{{ matrix_mautrix_signal_homeserver_domain|regex_escape }}$'
+    - exclusive: true
+      regex: '^@{{ matrix_mautrix_signal_appservice_bot_username|regex_escape }}:{{ matrix_mautrix_signal_homeserver_domain|regex_escape }}$'
     aliases:
     - exclusive: true
       regex: '^#signal_.+:{{ matrix_mautrix_signal_homeserver_domain|regex_escape }}$'
 url: {{ matrix_mautrix_signal_appservice_address }}
-sender_localpart: signalbot
+# See https://github.com/tulir/mautrix-signal/issues/43
+sender_localpart: _bot_{{ matrix_mautrix_signal_appservice_bot_username|to_json }}
 rate_limited: false
diff --git a/roles/matrix-bridge-mautrix-telegram/defaults/main.yml b/roles/matrix-bridge-mautrix-telegram/defaults/main.yml
index 7e072b5a..7ab200d0 100644
--- a/roles/matrix-bridge-mautrix-telegram/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-telegram/defaults/main.yml
@@ -30,6 +30,8 @@ matrix_mautrix_telegram_homeserver_domain: '{{ matrix_domain }}'
 matrix_mautrix_telegram_appservice_address: 'http://matrix-mautrix-telegram:8080'
 matrix_mautrix_telegram_appservice_public_external: 'https://{{ matrix_server_fqn_matrix }}{{ matrix_mautrix_telegram_public_endpoint }}'
 
+matrix_mautrix_telegram_appservice_bot_username: telegrambot
+
 # Controls whether the matrix-mautrix-telegram container exposes its HTTP port (tcp/8080 in the container).
 #
 # Takes an "<ip>:<port>" or "<port>" value (e.g. "127.0.0.1:9006"), or empty string to not expose.
@@ -109,10 +111,13 @@ matrix_mautrix_telegram_registration_yaml: |
       users:
       - exclusive: true
         regex: '^@telegram_.+:{{ matrix_mautrix_telegram_homeserver_domain|regex_escape }}$'
+      - exclusive: true
+        regex: '^@{{ matrix_mautrix_telegram_appservice_bot_username|regex_escape }}:{{ matrix_mautrix_telegram_homeserver_domain|regex_escape }}$'
       aliases:
       - exclusive: true
         regex: '^#telegram_.+:{{ matrix_mautrix_telegram_homeserver_domain|regex_escape }}$'
-  url: {{ matrix_mautrix_telegram_appservice_address }}
+  # See https://github.com/tulir/mautrix-signal/issues/43
+  sender_localpart: _bot_{{ matrix_mautrix_telegram_appservice_bot_username|to_json }}
   sender_localpart: telegrambot
   rate_limited: false
 
diff --git a/roles/matrix-bridge-mautrix-telegram/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-telegram/templates/config.yaml.j2
index d2848ec1..39a18462 100644
--- a/roles/matrix-bridge-mautrix-telegram/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-telegram/templates/config.yaml.j2
@@ -55,7 +55,7 @@ appservice:
     # The unique ID of this appservice.
     id: telegram
     # Username of the appservice bot.
-    bot_username: telegrambot
+    bot_username: {{ matrix_mautrix_telegram_appservice_bot_username|to_json }}
     # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
     # to leave display name/avatar as-is.
     bot_displayname: Telegram bridge bot
diff --git a/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml b/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
index beda6d7d..0467c3b7 100644
--- a/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
@@ -27,6 +27,8 @@ matrix_mautrix_whatsapp_systemd_wanted_services_list: []
 matrix_mautrix_whatsapp_appservice_token: ''
 matrix_mautrix_whatsapp_homeserver_token: ''
 
+matrix_mautrix_whatsapp_appservice_bot_username: whatsappbot
+
 
 # Database-related configuration fields.
 #
@@ -93,11 +95,14 @@ matrix_mautrix_whatsapp_registration_yaml: |
   url: {{ matrix_mautrix_whatsapp_appservice_address }}
   as_token: "{{ matrix_mautrix_whatsapp_appservice_token }}"
   hs_token: "{{ matrix_mautrix_whatsapp_homeserver_token }}"
-  sender_localpart: whatsappbot
+  # See https://github.com/tulir/mautrix-signal/issues/43
+  sender_localpart: _bot_{{ matrix_mautrix_whatsapp_appservice_bot_username|to_json }}
   rate_limited: false
   namespaces:
       users:
       - regex: '^@whatsapp_[0-9]+:{{ matrix_mautrix_whatsapp_homeserver_domain|regex_escape }}$'
         exclusive: true
+      - exclusive: true
+        regex: '^@{{ matrix_mautrix_whatsapp_appservice_bot_username|regex_escape }}:{{ matrix_mautrix_whatsapp_homeserver_domain|regex_escape }}$'
 
 matrix_mautrix_whatsapp_registration: "{{ matrix_mautrix_whatsapp_registration_yaml|from_yaml }}"
diff --git a/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
index 89216695..b3b1caf1 100644
--- a/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
@@ -36,7 +36,7 @@ appservice:
     # Appservice bot details.
     bot:
         # Username of the appservice bot.
-        username: whatsappbot
+        username: {{ matrix_mautrix_whatsapp_appservice_bot_username|to_json }}
         # Display name and avatar for bot. Set to "remove" to remove display name/avatar, leave empty
         # to leave display name/avatar as-is.
         displayname: WhatsApp bridge bot