gpgsm: smime, various secret keys, various email addresses how to configure

[Uwe Brauer]

Hello

I am not sure that this is the correct list to ask and whether my
question is too elementary, but I could not find a solution using google.

I started to use smime, via xemacs, gnus, epg and gpgsm. [1]

I have 3 accounts, one for work two private ones. I obtained free
certificates  from www.comodo.com.

Now the issue is that epg (the lisp interface) chooses the first secret
keys which is listed via 

 gpgsm --list-secrect-keys

For any email, even if I use a different account.

However I would like to have

 user1 at gmail.com key1
 user2 at gmail.com key2
 user3 at gmail.com key3

The epg author referred to the gpgsm manual or the mailing list, however
I can't find a relevant description 

Can somebody help me?

Thanks very much in advance

Uwe Brauer 

Footnotes:
[1]  I used gpg, but most of the people I correspondence considered it
     as to user unfriendly.