Disable abonnements for all new user

[Novo]

Hello,
I have vB4 running with sendmail under Debian.
After some time, the Forum slow down and all new posts are posted twice.

I searched why this happen and it seem sendmail is overloaded.
So i decided to disable auto abonnement for all new user.

Where can i disable the auto abonnement for all new user?
And where can i disable it for all existing user?

Mfg Novo

[Novo]

-.- thanks for answer.

[Videx]

There are some settings in Options>User Registration Options. For the more hardcore stuff you may need to run a query. Maintenance>Execute SQL Query>Auto query