From personal experience, if you're not jumping straight from no emails to a million an hour, your mail setup is good (SPF/DKIM/etc), you're not reusing a IP address that was sending spam last week (so be wary sending from cloud servers), and you aren't actually sending spam, then you can send from your own infrastructure just fine.
This is true, with the exception of AT&T. The Deathstar rejects all mail from my server, despite (a) no spam ever having been emitted from my domain in almost 20 years, (b) the IP having been stable for coming on eight years, and (c) I don't send bulk mail. Best I can tell, their blacklist-removal process is auto-deny with no humans in the loop.
I gave up and decided screw them, I don't need to talk to anyone with an ATT address, and bounce messages from them with an explanation.
I think AT&T was also the reason I started using a bulk mail delivery service for my low volume personal mail when 1&1 migrated their datacenter after I had been using them for a decade or something (thereby changing my IP address).
Until recently I sent newsletters from our own infrastructure and I agree that it's doable, but:
- You have to ramp up sending from new IP addresses VERY slowly if you want to avoid getting grey / black listed by Yahoo and AOL, this makes it quite a tedious process
- Make sure you also have rDNS set up, Gmail uses it as an important quality signal
- Accurately handling bounces is a bit of a nightmare because each mail server has a slightly different format and you want to make sure you don't process out-of-office messages
- Bounces and "message delayed" messages can arrive days later
So we ended up switching to mailgun and although they do sometimes give you a bad IP the time saved is worth it, especially their option to have a web hook back to your backend to process the bounces.
Sure. Until they email you your account is "temporarily suspended due to some spam complains" and before you find out some angry customer felt that tmher refund process took too long and filter her email to see yours and click "mark as spam" each email and you scramble to setup your own mailservers before you let employees go because your company is unable to send a single email to make a single sale this month...
Mine was suspended for spam and I was falsely accused by Mailgun of have compromised servers. Initially I freaked out and then discovered that my servers were fine, but my account at Mailgun was hacked and used to send thousands of spam emails. This happened a couple of times. I asked to see the IP addresses of the senders and Mailgun said they didn't track that/could not tell me. And then they had the audacity to bill me for sending spam that was sent as result of their system being compromised.
