diff --git a/app/models/ticket.rb b/app/models/ticket.rb
index 8568dc75c..d630dbce1 100644
--- a/app/models/ticket.rb
+++ b/app/models/ticket.rb
@@ -922,7 +922,7 @@ perform changes on ticket
               ticket_id: id,
               sender: Ticket::Article::Sender.find_by(name: 'System'),
               type: Ticket::Article::Type.find_by(name: 'email'),
-            ).where("ticket_articles.created_at > ? AND ticket_articles.to LIKE '%#{recipient_email.strip}%'", Time.zone.now - minutes.minutes).count
+            ).where('ticket_articles.created_at > ? AND ticket_articles.to LIKE ?', Time.zone.now - minutes.minutes, "%#{recipient_email.strip}%").count
             next if already_sent < count
             logger.info "Send no trigger based notification to #{recipient_email} because already sent #{count} for this ticket within last #{minutes} minutes (loop protection)"
             skip = true
@@ -941,7 +941,7 @@ perform changes on ticket
             already_sent = Ticket::Article.where(
               sender: Ticket::Article::Sender.find_by(name: 'System'),
               type: Ticket::Article::Type.find_by(name: 'email'),
-            ).where("ticket_articles.created_at > ? AND ticket_articles.to LIKE '%#{recipient_email.strip}%'", Time.zone.now - minutes.minutes).count
+            ).where('ticket_articles.created_at > ? AND ticket_articles.to LIKE ?', Time.zone.now - minutes.minutes, "%#{recipient_email.strip}%").count
             next if already_sent < count
             logger.info "Send no trigger based notification to #{recipient_email} because already sent #{count} in total within last #{minutes} minutes (loop protection)"
             skip = true
diff --git a/test/unit/email_process_test.rb b/test/unit/email_process_test.rb
index e2ecb83d7..3df6d1844 100644
--- a/test/unit/email_process_test.rb
+++ b/test/unit/email_process_test.rb
@@ -69,6 +69,45 @@ Some Textäöü",
           },
         },
       },
+      {
+        data: "From: me@exampl'e.com
+To: customer@exampl'e.com
+Subject: äöü some subject
+
+Some Textäöü",
+        channel: {
+          trusted: false,
+        },
+        success: true,
+        result: {
+          0 => {
+            priority: '2 normal',
+            title: 'äöü some subject',
+          },
+          1 => {
+            body: 'Some Textäöü',
+            sender: 'Customer',
+            type: 'email',
+            internal: false,
+          },
+        },
+        verify: {
+          users: [
+            {
+              firstname: '',
+              lastname: '',
+              fullname: 'me@exampl\'e.com',
+              email: 'me@exampl\'e.com',
+            },
+            {
+              firstname: '',
+              lastname: '',
+              fullname: 'customer@exampl\'e.com',
+              email: 'customer@exampl\'e.com',
+            },
+          ],
+        },
+      },
       {
         data: "From: me@example.com
 To: customer@example.com