Where to add sendmail path in modular muttconf

Question

I use folder hooks in mutt to be able to use it for multiple imap accounts.

I can access the different imap mailboxes without problem via key-bindings and can also switch between them.

I followed this little tutorial to achieve it.

multiple accounts in mutt using folder-hooks and seperate files I just cant figure out in which file the

set sendmail=/usr/sbin/sendmail

has to go in this case to be able to send mail to a remote smtp server.

.mutt is in ~/ and looks like this: (f is for file, d for directory)

(f)./account.muttrc
(d)./accounts
(d)./cache
(f)./certificates
(f)./muttrc
(f)./sources.muttrc

./sources.muttrc: speciefies multiple imap hosts, keybindings for switching between them, mutt-commands to execute for switching.

./accounts/accountx.muttrc: specifies from: address, imap & smtp credentials, some account-folder variables.

./account.muttrc: sourced everytime i switch the accounts

./muttrc: main configuration file looks like this:

# .mutt/muttrc
source ~/.mutt/sources.muttrc
folder-hook . source ~/.mutt/account.muttrc