diff --git a/src/dispatch/case/flows.py b/src/dispatch/case/flows.py
index fe362db9a714..88fc2ab48631 100644
--- a/src/dispatch/case/flows.py
+++ b/src/dispatch/case/flows.py
@@ -5,6 +5,7 @@
 from sqlalchemy.orm import Session
 
 from dispatch.case import service as case_service
+from dispatch.case.messaging import send_case_welcome_participant_message
 from dispatch.case.models import CaseRead
 from dispatch.conversation import flows as conversation_flows
 from dispatch.database.core import SessionLocal
@@ -129,6 +130,13 @@ def case_add_or_reactivate_participant_flow(
                 case, [participant.individual.email], db_session
             )
 
+        # we send the welcome messages to the participant
+        send_case_welcome_participant_message(
+            participant_email=user_email,
+            case=case,
+            db_session=db_session
+        )
+
     return participant
 
 
diff --git a/src/dispatch/case/messaging.py b/src/dispatch/case/messaging.py
index d59f7325c58f..2d21377328d0 100644
--- a/src/dispatch/case/messaging.py
+++ b/src/dispatch/case/messaging.py
@@ -29,6 +29,7 @@
 from dispatch.plugin import service as plugin_service
 from dispatch.event import service as event_service
 from dispatch.notification import service as notification_service
+from dispatch.plugins.dispatch_slack.case.messages import create_welcome_ephemeral_message_to_participant
 
 from .enums import CaseStatus
 
@@ -302,3 +303,33 @@ def send_case_update_notifications(
     )
 
     log.debug("Case updated notifications sent.")
+
+
+def send_case_welcome_participant_message(
+    *,
+    participant_email: str,
+    case: Case,
+    db_session: Session,
+):
+    if not case.dedicated_channel:
+        return
+
+    plugin = plugin_service.get_active_instance(
+        db_session=db_session, project_id=case.project.id, plugin_type="conversation"
+    )
+
+    if not plugin:
+        log.warning(
+            "Case participant welcome message not sent. No conversation plugin enabled."
+        )
+        return
+
+    welcome_message = create_welcome_ephemeral_message_to_participant(case=case)
+    plugin.instance.send_ephemeral(
+        conversation_id=case.conversation.channel_id,
+        user=participant_email,
+        text=f"Welcome to {case.name}",
+        blocks=welcome_message,
+    )
+
+    log.debug(f"Welcome ephemeral message sent to {participant_email}.")
diff --git a/src/dispatch/plugins/dispatch_slack/case/interactive.py b/src/dispatch/plugins/dispatch_slack/case/interactive.py
index e401784d8717..c8fc8574f5f2 100644
--- a/src/dispatch/plugins/dispatch_slack/case/interactive.py
+++ b/src/dispatch/plugins/dispatch_slack/case/interactive.py
@@ -5,7 +5,6 @@
 from functools import partial
 import json
 import pytz
-import re
 
 from blockkit import (
     Actions,
@@ -58,7 +57,6 @@
 from dispatch.plugins.dispatch_slack.case.messages import (
     create_case_message,
     create_signal_engagement_message,
-    create_welcome_ephemeral_message_to_participant,
 )
 from dispatch.plugins.dispatch_slack.config import SlackConversationConfiguration
 from dispatch.plugins.dispatch_slack.decorators import message_dispatcher
@@ -97,7 +95,6 @@
     SignalSubjects,
     SubjectMetadata,
 )
-from dispatch.plugins.dispatch_slack.service import get_user_email
 from dispatch.project import service as project_service
 from dispatch.search.utils import create_filter_expression
 from dispatch.signal import service as signal_service
@@ -939,53 +936,6 @@ def handle_new_participant_message(
     participant.user_conversation_id = context["user_id"]
 
 
-@message_dispatcher.add(
-    subject=CaseSubjects.case, exclude={"subtype": ["channel_join", "channel_leave"]}
-)  # we ignore channel join and leave messages
-def handle_new_participant_added(
-    ack: Ack,
-    payload: dict,
-    context: BoltContext,
-    db_session: Session,
-    client: WebClient,
-) -> None:
-    """Looks for new participants being added to conversation via @<user-name>"""
-    ack()
-    participants = re.findall(r"\<\@([a-zA-Z0-9]*)\>", payload["text"])
-    for user_id in participants:
-        try:
-            case: Case = context["subject"]
-            user_email = get_user_email(client=client, user_id=user_id)
-
-            # check if user is already a participant
-            participant = participant_service.get_by_case_id_and_email(
-                db_session=db_session, case_id=case.id, email=user_email
-            )
-
-            if participant and participant.active_roles:
-                continue
-
-            participant = case_flows.case_add_or_reactivate_participant_flow(
-                case_id=case.id,
-                user_email=user_email,
-                db_session=db_session,
-                add_to_conversation=False,
-            )
-            participant.user_conversation_id = user_id
-
-            case = case_service.get(db_session=db_session, case_id=case.id)
-            if case.dedicated_channel:
-                welcome_message = create_welcome_ephemeral_message_to_participant(case=case)
-                client.chat_postEphemeral(
-                    blocks=welcome_message,
-                    channel=payload["channel"],
-                    user=user_id,
-                )
-        except Exception as e:
-            log.warn(f"Error adding participant {user_id} to Case {context['subject'].id}: {e}")
-            continue
-
-
 @message_dispatcher.add(
     subject=CaseSubjects.case, exclude={"subtype": ["channel_join", "channel_leave"]}
 )  # we ignore channel join and leave messages