Mail goes to random unrelated tickets - Handling customers with OTRS

[Tommyrelli]

Hi! I'm new to the forum, I hope this is the right place to ask.

My company is using OTRS Community Edition (v5.0) and everything is fine.

Issue is, now we are having some mail exchanges with another helpdesk company which uses OTRS aswell, so when they reply to a mail of ours automatically placing their ticket number to object/body of the email, it goes straight to our unrelated ticket numbered like theirs.

For example:

1) From US to Company

Associated ticket on our OTRS:
Ticket#2021042210000039 - Please send us some papers

Object:
[Ticket#2021041610000039] Please send us some papers
Body:
We really need papers, please send some.
Best regards, US

2) Reply from Company to US

Associated ticket on our OTRS:
Ticket#2021042210000045 - (Totally unrelated ticket from another customer)

Object:
Re: [Ticket#2021042210000045] [Ticket#2021041610000039] Please send us some papers
Body:
You have been given the ticket n° 2021042210000045


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Is there any way to prevent this?
Where do I set up so that mails coming from "Company Address" don't go into already existing tickets, but rather ALWAYS create new ones so i can manually merge them later?

[root]

Hi,

Looks like both of you use the SystemID 10.
I recommend changing the SystemID, configure the system configuration Ticket::NumberGenerator::CheckSystemID to no and use on of the
PostMaster::PreFilterModule###000-ExternalTicketNumberRecognition filter.

- Roy