Recommend a primitive linux mail server that only forwards mail

Question

linux

the essence is this: there is one VPS, so as not to waste memory and not produce processes, I want to install a simple mail daemon that will redirect all incoming mail to another mailbox without exception. but which would correctly send out outgoing mail from sites hosted on the VPS, such as password reminders, new messages, etc. memory requirements are critical.

Answer 1

SSMTP, although its development has been discontinued, as far as I know. As an alternative - MSMTP.
XMail is also a good option.

Answer 2

exim.

Answer 3

XMail
www.xmailserver.org/

Answer 4

I came across nullmailer, but it only uses external smtp to send outgoing mail, as far as I understand, and cannot accept mail itself for subsequent forwarding.
settled on sendmail. sending from localhost is fine, plus root:[email protected] is written in /etc/aliases - for all forwarding to an external address.