SMTP doesn't just drop messages if the destination server is unavailable. It'll either get held back at an intermediary server until your server comes up again, or else it will be bounced back to the sender.
That's not true. It should either send the email to the recipient or return it to sender. But it should never just drop the message (except for bounces which can be dropped since there is nowhere to send them if delivery fails).
I think you and the parent are using different meanings of "guarantee."
Yes, everything in the protocol leads to the fact that nothing should drop an email unless it has passed responsibility of it to another server which has accepted the message.
Yes, one misconfigured server between source and destination can "eat" email and you'll never be the wiser. Doesn't happen often, but it can and the protocol does not detect it.
An SMTP daemon will try to send the message a certain number of times, at a certain interval, then, eventually, it will stop ("bounce"). You can configure these settings if you run your own SMTP service.
I risk new messages getting bounced, but all of my email is backed up on my computer. And I'd archive everything to s3 (which has never lost data to my knowledge) in case both my ec2 instance and my laptop disappeared.
You can set up a different mail server with a lower priority. I run my own server on a VPS, but have Google Apps' SMTP server as backup for those cases, and it's been working fine for months.
Assuming your ISP is not blocking port 25 and your internet address is not on some blacklist you can send mail directly from your machine. No need to use intermediary SMTP servers.
Is it possible that someone people might like to use their native SMTP capability for low volume noncommercial email? Does every person who sends email have some overwhelming urge to send spam? Such that we must place pseudo control over sending email, any email whether commercial or noncommercial, in the hands of "email providers"?
My ISP doesn't block port 25, but since my IP address is technically dynamic, it's on Spamhaus' Policy Black List. That said, my ISP offers SMTP servers for proxying outgoing messages, so I used that for a while. I switched to a VPS because my home server died.
"Spammers use cheap dynamic IP's therefore anyone with a cheap dynamic IP that sends an email is a spammer."
That's not what they're saying.
"Very many spam emails come from people running an email server on a dynamic IP. Some companies were happy to host spam sending companies, and would put them in dynamic ranges so they could continue to get money from those spam sending companies and keep changing the IP address. The ratio of good email servers to bad email servers on dynamic IPs is so poor that blocking all dynamic IPs is, unfortunately, the only reasonably solution".
You can be on a dynamic IP and send email. Just don't send that email from a server on a dynamic IP.
What they're doing is making a very dodgey assumption. They might stop a few hundred potential spammers but they also stop millions of people who could potentially be using email more effiently and reliably (and Spam Free) by sending and/or receiving mail directly between their machines.
Email could be even more decentralized than it already is in practice. This could potentially make spam far more difficult.
Reading that quote (from SpamHaus?) two things come to mind:
1. We are entrusting the rules on our mail delivery to someone who begins sentences with "Very many" and lacks the attention to detail to spell "reasonable" correctly. Make of that what you will.
2. The "problem" is not the existence of "bad email servers" on dynamic IP's, it is the lack of "good email servers" on dynamic IP's. Why the heck aren't the millions of people on dynamic IP's using this capability? Answer: They do not know it exists.
To "replace email", we do not necessarily need to fundamentally change anything about how email works. What we need to do, perhaps, is replace the people controlling it and instruct "good" people how it works. As it stands, in general, the only folks who understand how email works are a. email providers (e.g. ISP's), b. spammers and c. spam fighters.
If the vast majority of email sent directly to recipients from dynamic IP's was low volume and noncommercial, the "bad apples" would be overshadowed by the good ones. And so would the anti-spam zealots be overshadowed by reasonable people who just want to communicate with each other (not necessarily trying to sell ED treatments to the whole of humanity).
Education is the way forward. People arguing against any sort of consumer education on something so basic as internet messaging are an interesting spectacle to behold. Their attitude should fuel the fire of anyone working on this "dangerous idea" of "replacing email". You know who you are.
Well, yes, because my ISP only offers static IPs for business contracts, which are more expensive overall, and my VPS only costs $2.3/month (and it doubles as a web server, hosting my personal landing page and an instance of Tiny Tiny RSS).