[exim] can we thread mails in exim

Hi All,

I want to try email threading in exim, can you please suggest how it can be
done or is there any documentation where I can read about that.

I have to thread mail sent from multiple servers to one *outlook* inbox.
example: s1,s2,s3,s4 sending mail to r1 , then all the mails of s1,s2 and
s3 are threaded in the mailbox of r1, without r1 replying to any mail.
These are similar kinds of mail.

Thank you in advance.

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