Salary In Lieu Of Notice Period

I have been working as a Manager in a partnership firm since April 2014. I have an appointment letter but no confirmation letter has been issued. This April my leaves calculation has been done on the basis of confirmed employees.
I have now received an email asking me to leave the company today i.e. 30th Sep and hand over charge to a colleague.
I would like to leave immediately but also get 1 months salary in lieu of notice. Is my argument for this legally tenable?
HR experts kindly advise.

Dear Vimal,
What does your Appointment Letter state about the confirmation clause, Does it state that you would be deemed confirmed after a particular period or it says, that you would not be considered confirmed unless shared with you in writing.
Also what is the clause in the appointment in regards to the notice period from both side?
Regards,
Ashutosh Thakre

Yes as mentioned above, it is purely based on the clauses given in the appointment order.

There is no deemed confirmation under normal circumstances. Therefore, unless specifically written, confirmation will happen only when communicated in writing. An employee under probation may be terminated without notice and without assigning any reason. Moreover, the matter pertains to a Manager who will not get any protection from law. But before sending an employee out, the employer should have followed at least the basics of principles of natural justice. In this case, you should have been given a notice before asking you to leave in a fine morning.
Madhu.T.K