diff --git a/app/models/channel/filter/follow_up_check.rb b/app/models/channel/filter/follow_up_check.rb
index bafa49762..d41d32ff0 100644
--- a/app/models/channel/filter/follow_up_check.rb
+++ b/app/models/channel/filter/follow_up_check.rb
@@ -18,7 +18,7 @@ module Channel::Filter::FollowUpCheck
 
     # get ticket# from body
     if setting.include?('body')
-      ticket = Ticket::Number.check(mail[:body])
+      ticket = Ticket::Number.check(mail[:body].html2text)
       if ticket
         Rails.logger.debug { "Follow up for '##{ticket.number}' in body." }
         mail['x-zammad-ticket-id'.to_sym] = ticket.id
@@ -30,7 +30,7 @@ module Channel::Filter::FollowUpCheck
     if setting.include?('attachment') && mail[:attachments]
       mail[:attachments].each do |attachment|
         next if !attachment[:data]
-        ticket = Ticket::Number.check(attachment[:data])
+        ticket = Ticket::Number.check(attachment[:data].html2text)
         next if !ticket
         Rails.logger.debug { "Follow up for '##{ticket.number}' in attachment." }
         mail['x-zammad-ticket-id'.to_sym] = ticket.id
diff --git a/app/models/ticket/number/date.rb b/app/models/ticket/number/date.rb
index e32b53874..a939e3297 100644
--- a/app/models/ticket/number/date.rb
+++ b/app/models/ticket/number/date.rb
@@ -86,12 +86,12 @@ module Ticket::Number::Date
     end
 
     # probe format
-    string.scan(/#{Regexp.quote(ticket_hook)}#{Regexp.quote(ticket_hook_divider)}(\d{4,10}#{system_id}\d{2,40})/i) do
+    string.scan(/\b#{Regexp.quote(ticket_hook)}#{Regexp.quote(ticket_hook_divider)}(\d{4,10}#{system_id}\d{2,40})\b/i) do
       ticket = Ticket.find_by(number: $1)
       break if ticket
     end
     if !ticket
-      string.scan(/#{Regexp.quote(ticket_hook)}\s{0,2}(\d{4,10}#{system_id}\d{2,40})/i) do
+      string.scan(/\b#{Regexp.quote(ticket_hook)}\s{0,2}(\d{4,10}#{system_id}\d{2,40})\b/i) do
         ticket = Ticket.find_by(number: $1)
         break if ticket
       end
diff --git a/app/models/ticket/number/increment.rb b/app/models/ticket/number/increment.rb
index 0e5b0d9a7..adbc39281 100644
--- a/app/models/ticket/number/increment.rb
+++ b/app/models/ticket/number/increment.rb
@@ -83,12 +83,12 @@ module Ticket::Number::Increment
     end
 
     # probe format
-    string.scan(/#{Regexp.quote(ticket_hook)}#{Regexp.quote(ticket_hook_divider)}(#{system_id}\d{2,48})/i) do
+    string.scan(/\b#{Regexp.quote(ticket_hook)}#{Regexp.quote(ticket_hook_divider)}(#{system_id}\d{2,48})\b/i) do
       ticket = Ticket.find_by(number: $1)
       break if ticket
     end
     if !ticket
-      string.scan(/#{Regexp.quote(ticket_hook)}\s{0,2}(#{system_id}\d{2,48})/i) do
+      string.scan(/\b#{Regexp.quote(ticket_hook)}\s{0,2}(#{system_id}\d{2,48})\b/i) do
         ticket = Ticket.find_by(number: $1)
         break if ticket
       end
diff --git a/spec/models/channel/email_parser_spec.rb b/spec/models/channel/email_parser_spec.rb
index 85b1017c0..49ffaccdf 100644
--- a/spec/models/channel/email_parser_spec.rb
+++ b/spec/models/channel/email_parser_spec.rb
@@ -28,6 +28,24 @@ RSpec.describe Channel::EmailParser, type: :model do
               .to change { ticket.articles.length }
           end
         end
+
+        context 'as part of a larger word' do
+          let(:raw_mail) { File.read(mail_file).sub(/(?<=Hallo) =\n(?=Martin,<o:p>)/, test_string) }
+
+          it 'creates a separate ticket' do
+            expect { described_class.new.process({}, raw_mail) }
+              .not_to change { ticket.articles.length }
+          end
+        end
+
+        context 'in html attributes' do
+          let(:raw_mail) { File.read(mail_file).sub(%r{<a href.*?/a>}m, %(<table bgcolor="#{test_string}"> </table>)) }
+
+          it 'creates a separate ticket' do
+            expect { described_class.new.process({}, raw_mail) }
+              .not_to change { ticket.articles.length }
+          end
+        end
       end
     end
   end