Sms to email. Problem with sendmail

i manage board (SMS with keyword Balance forward to mybox@email.domen)

when i see log

sendmail # start from:xxx@xxx.xx to:yyy@yyy.yy subject:[BALANCE] SMS board from +zzzzzzzzz
sendmail # end with error:Connection refused could not connect to the host “localhost”

When i check sendmail at console all ok: mail sending. And i receive it.

what service send email? What headers use?

Consider using postfix