Notyfication to Customer User without OTRS account.

[KepTom]

To understanding my problem I describe our situation.
My company provides outsourcing IT services.
Customer user in companies that we support change frequently. We don't create accounts for all customer user. Only for VIP and managers.
It would be too cumbersome.

We accept ticket by e-mail and phone. With phone ticket we don't have a problem because they are registere by agents.
We have problem with ticket from e-mail
Customer user send his problem by email to our otrs mail address. On input we use postmaster filter which connect ticket to CustomerID by customer mail domain.
And now appears the problem, because services are connected to named (in OTRS) Customer User, not to Customer.
In this situation we can't assign services and SLA to ticket.
We can change Customer User to named (in OTRS) Customer User for example ACME.Office and assign services but in this situation the User that sent the e-mail will not receive a notyfication ticket changes
Notification will be send to ACME.Office e-mail.

Is there any way around this ?

P.S.
When I create ticket by PhoneTicket I can add named Customer User (ex. ACME.Office) and e-mail of user who call.
Sorry for my English

[crythias]

perhaps a not-so-nice way is to check domain and assign both user and customer_id (customer_no) of an account you already have.

[KepTom]

Yes and No
e.g.
We have Company - ACME (CustomerID - acme)
We have 3 accounts for ACME Company User:
manager1 (CustomerID - acme) <manager1@acme.com>
manager2 (CustomerID - acme) <manager2@acme.com>
office (CustomerID - acme) <office@null.com> - for rest of the Acme Company Users.

In described situation:
A Company User e.g <user1@acme.com> send e-mail to our OTRS system and we record it as ticket.
After Postmaster Filter (From @acme.com set CustomerID=acme) we get ticket with :
From: <user1@acme.com>
CustomerID=acme
Customer_User_ID=user1@acme.com

After that user1@acme.com will receive AutoReply with info about new ticket, but system doesn't know user1@acme.com and we can't add the service for this user.
System doesn't have relations user1@acme.com <-> services.
I need to change CustomerUser to office@acme.com and now I can add the service but after this when I close ticket, a notification will be sent to office@null.com but not to user1@acme.com
When I change CustomerUserID on postmasterfilter we have this same situations.

It's any way to change it - send notification to Ticket sender too ?