For the parent post, you configure an outgoing SMTP relay
Iirc called smarthost in postfix
A user's inbound mail accumulates on a mail server. One server [protocol] handles getting the user's inbound mail to that user's mail client -- usually with protocols like POP or IMAP that let the user retrieve that accumulation.
Another server handles whatever mail the user decides to send, using SMTP. Each server is configured within the user's mail client, and that's just the normal way of doing things. It's ~always been split up like this (aside from outliers like Microsoft Exchange). :)
The user doesn't have to know anything about the existence or addition of a system like smtp2go. They just configure their client to send mail through mail.orgname.com (or whatever) like usual, and the back end handles the rest. Their pop/imap server address also stays the same.
---
Anyway, mail servers and relays. Mail servers don't talk to eachother using things like POP or IMAP. The traditional Internet way for a mail server to send mail to another is to look up the recipient domain's MX (Mail eXchanger) entry in DNS, which specifies the inbound mail server, and just send it over using SMTP.
It was thus delivered. It was all very trusting.
That trust began to break when spam became a problem that never went away. Requirements and reputation and filtering became a serious ordeal for mail servers -- both on the sending and the receiving side of things.
Services like smtp2go can handle part of the sending-side trust-wizardry in a centralized way. They do things like maintain the reputation of their IP addresses.
In using it like this, orgname's server (which might very well be under someone's desk) ceases to directly connect to each and every recipient domain's MX.
It goes through smtp2go instead: All outbound mail simply gets routed through smtp2go, as the result of a central back-end configuration thing on orgname's mail server.
In email terms this is called relaying, though smtp2go might prefer the term smarthost[1].
Meanwhile, local internal mail (from joe@orgname to jill@orgname, say) can just get delivered locally. It doesn't have to be relayed at all. This determination is made by orgname's mail server.
And, again: The user doesn't need to know or care that their mail is/isn't being relayed, and the concept of relays themselves is as old as the hills. The user can just be happy that their mail gets where it needs to go instead of being silently dumped into a ditch, and they don't need to do anything different on their end for this to happen.
When sending the other side is the server, when receiving, you are the one. The protocol also has the concept of relaying, where message can go trough intermediary nodes.
So you can set one server for receiving email (yours) and another one for sending (smtpgo).
For actually reading, the server for receiving need to deliver the message (either built-in feature or through a program) to the correct mailbox. That would probably means writing it on disk somewhere. And then you need to use a mail user agent (MUA) to read that file. Protocol like imaps and pop3 are for transfering your inbox to another computer, not for receiving or delivering email.
If they would at least dump it in the junk mail folder, I could fix it, but no, some earlier step in the process makes it silently disappear.
- Outlook.com consumer mail addresses
you can still get >99% delivery rate if you have spf, dkim and all the new cool stuff.
So no, please DO NOT recommend against doing it because ONLY if mail stays a decentralized service providers will stay forced to not blacklist everything but other large providers.
You don’t build your own fridge. If it’s important and not your strong suit, pay someone to do it for you.
In my professional life I managed email infrastructures since 20 years ago. It only got harder.
If you achieve 100% delivery rate you will surely share the results, right? No? Oh i guess all those services simply tell you they make it easier for you while not actually achieving that - but why check?
Just too critical of a component in most people's lives to accept any level of unknowns in.
1. IP reputation is a big deal, its not just about not being on some blocklist, call it a cartel at this point, its about being on the allow list for other mail providers
2. Keeping it reputable is a continuous effort
Never had any issues since then, though I did have to adjust to new standards such as DKIM, DMARC, SPF etc. over the years.
AFAIK, that case in 2019 was the only time an e-mail went missing.
Yea we do all the best practices but still no one can guarantee 100% deliveries. Just not possible for e-mail.
Yes we can have 100% over a year but after that it still is a lottery, can’t say anything about future not having suddenly 40% not delivered
I still self-host, but now I cheat for deliverability: route the problematic destinations (I'm looking at you, Outlook) through Amazon SES. At a few cents for five-figure numbers of emails, it's as close to free for personal/vanity email quantities as it gets to have someone whose full time job it is to make sure outgoing mail stays deliverable on your side while still keeping everything else under your control.
One thing to note is that Amazon are not very good at keeping amazonses.com up to date, so despite including it you can't set DMARC to hard-fail SPF or you will have mail bounce days.
4 different countries, different AS.
I'm always puzzled by all the issues described by others. I had about 4 issues during these 15 years, all 4 were solved by reading the bounce message and doing what was asked in the message (contacting support of the destination).
Took about 6 months initially of fiddling to get other email services to accept mail DKIM, DMARC, SPF, PTR, web form requests
The comments (not parents') are usually very weird like people are mad at us for hosting our own mail server or something. That is really an interesting phenomenon.
And on the deliverability side, using SES for sending avoids this entirely. Yes, ok, not fully self-hosted I suppose, but it's close enough (and for most people, the bill will be pennies).
So frustrating because they have no legal obligation to accept our emails but our product relies on them being delivered.
I gave up and moved everyone over to SES instead.
Not sure if that's still the case
That's cheaper than I can rent any mail-capable VPS for, and it's cheaper than the electricity I'd pay (80W @ $0.15/kWh = $316 over 3 years) to self-host.
And that doesn't include my personal-time hourly cost.
The last small-corpo email server I ran myself was a Pentium 4 box that worked for eons. It did all of the things (the spam filtering, the virus scanning, the tossing, the software RAID storage, the open internet-facing ports including the webmail) for all of the people.
But it turned out that even with dozens of users, it hardly ever saw any load. Email was a complete snoozefest for it.
I'm quite confident that an N100 box would run circles around that P4 machine using any metric, and use an average of less than 10 Watts if all it needs to do is serve mail at home.
You can certainly rent a mail-capable VPS less. Especially if you send emails through the AWS mail service. A small home server capable of hosting mail will absolutely not use 80W. It will use <10w.
But I encourage everyone who likes tech and freedom to host their own email. So many reasons.
Some are pragmatic, for example that way you won't ever get locked out suddenly of your entire digital existence when google/microsoft decide to lock you out for no reason and you will never reach support capable of helping.
Some are more about taking a stand for freedom, but that's also worthwhile. The internet was not meant to be owned by just a few behemots who get to control all content. The internet is about distributed peer to peer protocols. Nothing embodies that better than everyone running their own mail server, if you can.
As many say below, if you're worried about the deliverability you can still run your own email server and have nearly all the benefits even if you use a third party relay for delivery.
That said I also deliver from my email server and it is totally fine, the fears are overhyped. Delivery to microsoft is the worst, but even that one just takes filling a form on occasions (been over a year since had to do it last time).
No deliverability problems. The issues with self-hosting email are drastically overblown.
I was running Postfix+Dovecot+Seive+SpamAssassin+Fail2ban+certbot+spf+dkim+reverse-ip+<other random crap>
It worked! Receiving email was overall pretty easy. I know I also did things the "hard way" by ad-hoccing all that together, and today there are a lot more out-of-the-box solutions that do all that for you. But still. Being a full-time email administrator is a job I will never do again unless I'm getting paid for it.
You know what really sucked? Deliverability. Frequently, emails I would send would just ... vanish ... no warnings, no errors, no failures. From my end, everything was perfect. Until days later, people would follow up with me and say, "Are you going to send that email?" ...
I had a business IP (Comcast Business). The IP address was clean, not black listed anywhere, not on SORBS or other lists. Still, successfully delivering an email was like 50/50, with no way to confirm the other party actually got it.