OK yeah I think I see what you're saying, if the SMTP mailer is a hosted service and we're talking about the logs for the service itself then failed connections are not an error - this I agree with. I also wouldn't be logging anything transactional at all in this case - the transactional logs are for the user, they are functionality of the service itself in that case, and those logs should absolutely log a failure to connect as an error.
It doesn't matter if it is a hosted service or if its just your local mail transfer agent, every "SMTP mailer" works the same way. There are lots of ways to send email that don't involve a locally administered SMTP mailer (such as an API which indeed has a connection string to a hosted service) but none would be described with that term.