diff --git a/server-plugins/activity-resources/src/utils.ts b/server-plugins/activity-resources/src/utils.ts
index 31c2e67920..b24b77b5d0 100644
--- a/server-plugins/activity-resources/src/utils.ts
+++ b/server-plugins/activity-resources/src/utils.ts
@@ -1,4 +1,5 @@
 import {
+  Account,
   AttachedDoc,
   Class,
   Doc,
@@ -16,6 +17,9 @@ import {
 import core from '@hcengineering/core/lib/component'
 import { DocAttributeUpdates, DocUpdateAction } from '@hcengineering/activity'
 import { ActivityControl, DocObjectCache, getAllObjectTransactions } from '@hcengineering/server-activity'
+import { getDocCollaborators } from '@hcengineering/server-notification-resources'
+import notification from '@hcengineering/notification'
+import { TriggerControl } from '@hcengineering/server-core'
 
 function getAvailableAttributesKeys (tx: TxCUD<Doc>, hierarchy: Hierarchy): string[] {
   if (hierarchy.isDerived(tx._class, core.class.TxUpdateDoc)) {
@@ -143,17 +147,54 @@ export async function getDocDiff (
   return { doc, prevDoc }
 }
 
-export function getAttributeDiff (
-  hierarchy: Hierarchy,
+interface AttributeDiff {
+  added: DocAttributeUpdates['added']
+  removed: DocAttributeUpdates['removed']
+}
+
+async function getCollaboratorsDiff (
+  control: ActivityControl,
+  doc: Doc,
+  prevDoc: Doc | undefined
+): Promise<AttributeDiff> {
+  const { hierarchy } = control
+  const value = hierarchy.as(doc, notification.mixin.Collaborators).collaborators ?? []
+
+  let prevValue: Ref<Account>[] = []
+
+  if (prevDoc !== undefined && hierarchy.hasMixin(prevDoc, notification.mixin.Collaborators)) {
+    prevValue = hierarchy.as(prevDoc, notification.mixin.Collaborators).collaborators ?? []
+  } else if (prevDoc !== undefined) {
+    const mixin = hierarchy.classHierarchyMixin(prevDoc._class, notification.mixin.ClassCollaborators)
+    prevValue = mixin !== undefined ? await getDocCollaborators(prevDoc, mixin, control as TriggerControl) : []
+  }
+
+  const added = value.filter((item) => !prevValue.includes(item)) as DocAttributeUpdates['added']
+  const removed = prevValue.filter((item) => !value.includes(item)) as DocAttributeUpdates['removed']
+
+  return {
+    added,
+    removed
+  }
+}
+
+export async function getAttributeDiff (
+  control: ActivityControl,
   doc: Doc,
   prevDoc: Doc | undefined,
   attrKey: string,
   attrClass: Ref<Class<Doc>>,
   isMixin: boolean
-): { added: DocAttributeUpdates['added'], removed: DocAttributeUpdates['removed'] } {
+): Promise<AttributeDiff> {
+  const { hierarchy } = control
+
   let actualDoc: Doc | undefined = doc
   let actualPrevDoc: Doc | undefined = prevDoc
 
+  if (isMixin && hierarchy.isDerived(attrClass, notification.mixin.Collaborators)) {
+    return await getCollaboratorsDiff(control, doc, prevDoc)
+  }
+
   if (isMixin) {
     actualDoc = hierarchy.as(doc, attrClass)
     actualPrevDoc = prevDoc === undefined ? undefined : hierarchy.as(prevDoc, attrClass)
@@ -247,7 +288,7 @@ export async function getTxAttributesUpdates (
     }
 
     if (Array.isArray(attrValue) && doc != null) {
-      const diff = getAttributeDiff(hierarchy, doc, prevDoc, key, attrClass, isMixin)
+      const diff = await getAttributeDiff(control, doc, prevDoc, key, attrClass, isMixin)
       added.push(...diff.added)
       removed.push(...diff.removed)
       attrValue = []
diff --git a/server-plugins/notification-resources/src/index.ts b/server-plugins/notification-resources/src/index.ts
index cf9ddb8c23..9d41c6ccb1 100644
--- a/server-plugins/notification-resources/src/index.ts
+++ b/server-plugins/notification-resources/src/index.ts
@@ -681,12 +681,16 @@ async function updateCollaboratorsMixin (
   activityMessages: ActivityMessage[],
   originTx: TxCUD<Doc>
 ): Promise<Tx[]> {
+  const { hierarchy } = control
+
   if (tx._class !== core.class.TxMixin) return []
   if (originTx.space === core.space.DerivedTx) return []
-  if (!control.hierarchy.isDerived(tx.mixin, notification.mixin.Collaborators)) return []
+  if (!hierarchy.isDerived(tx.mixin, notification.mixin.Collaborators)) return []
+
   const res: Tx[] = []
+
   if (tx.attributes.collaborators !== undefined) {
-    const createTx = control.hierarchy.isDerived(tx.objectClass, core.class.AttachedDoc)
+    const createTx = hierarchy.isDerived(tx.objectClass, core.class.AttachedDoc)
       ? (
           await control.findAll(core.class.TxCollectionCUD, {
             'tx.objectId': tx.objectId,
@@ -701,12 +705,21 @@ async function updateCollaboratorsMixin (
     const mixinTxes = await control.findAll(core.class.TxMixin, {
       objectId: tx.objectId
     })
-    const prevDoc = TxProcessor.buildDoc2Doc([createTx, ...mixinTxes].filter((t) => t._id !== tx._id)) as Collaborators
-    const prevDocMixin = control.hierarchy.as(prevDoc, notification.mixin.Collaborators)
-    const set = new Set(prevDocMixin?.collaborators ?? [])
+    const prevDoc = TxProcessor.buildDoc2Doc([createTx, ...mixinTxes].filter((t) => t._id !== tx._id)) as Doc
     const newCollabs: Ref<Account>[] = []
+
+    let prevCollabs: Set<Ref<Account>>
+
+    if (hierarchy.hasMixin(prevDoc, notification.mixin.Collaborators)) {
+      const prevDocMixin = control.hierarchy.as(prevDoc, notification.mixin.Collaborators)
+      prevCollabs = new Set(prevDocMixin.collaborators ?? [])
+    } else {
+      const mixin = hierarchy.classHierarchyMixin(prevDoc._class, notification.mixin.ClassCollaborators)
+      prevCollabs = mixin !== undefined ? new Set(await getDocCollaborators(prevDoc, mixin, control)) : new Set()
+    }
+
     for (const collab of tx.attributes.collaborators) {
-      if (!set.has(collab)) {
+      if (!prevCollabs.has(collab) && tx.modifiedBy !== collab) {
         if (
           await isAllowed(
             control,
diff --git a/server-plugins/notification-resources/src/utils.ts b/server-plugins/notification-resources/src/utils.ts
index 7f19f41461..c840e5fc02 100644
--- a/server-plugins/notification-resources/src/utils.ts
+++ b/server-plugins/notification-resources/src/utils.ts
@@ -117,9 +117,9 @@ export async function isShouldNotify (
   )
 
   const personAccount = await getPersonAccountById(user, control)
+  const modifiedAccount = await getPersonAccountById(tx.modifiedBy, control)
 
   for (const type of types) {
-    const modifiedAccount = await getPersonAccountById(tx.modifiedBy, control)
     if (
       type.allowedForAuthor !== true &&
       (tx.modifiedBy === user ||