Sendmail might be a bit more popular than OpenSMTPD. We know about 1 link to it since March 2021 and only 1 link to OpenSMTPD. We are tracking product recommendations and mentions on Reddit, HackerNews and some other platforms. They can help you identify which product is more popular and what people think of it.
When I installed Rspamd with on OpenBSD / OpenSMTPD the other day, DKIMProxy out (dkimproxy_out daemon), which had been got via OpenBSD Ports package system, was used to add DKIM signatures to mails in order to improve security on emails. - Source: dev.to / 4 months ago
We are using sendmail and Exchange online with to different identies. We are experience problem that we want to receive Teams invitation to our @ sendmail.com address, when I forward teams invitation fromexchange online identite to "sendemail" identetie we are getting error. - Source: Reddit / 7 months ago
Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
sSMTP - sSMTP is a simple MTA to deliver mail from a computer to a mail server.
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
msmtp - msmtp is an SMTP client.
PowerMTA - PowerMTA is an industrial-strength software for high-volume email delivery.
Haraka - Open source SMTP server written in Node.js