[wampus]

I've run mail servers for decades without configuring them and have never had issues. Reputation is probably the most important (note that my domains and even some of my servers were online before these technologies existed) and it's extremely important to get your DNS right, especially Forward-confirmed reverse DNS (FCrDNS). Strictly enforce authentication on submission port 587 and segregate user submissions from application generated submissions so you can tweak each configuration appropriately. Keep in mind that marking messages as spam involves a complex chain of weighting, so if a minor adjustment gets your messages accepted, you could still be straddling a line and would benefit from fixing the basics. And never launch a server on an IP without first checking it against blacklists (demand a new one if it's listed anywhere).

[dchest]

Reputation is everything, but when you need to setup a new server on a new blacklist-checked IP for (non-spammy) mass mailing, without SPF and DKIM your emails will most likely go to the Spam folder, in 2015.

Of course, those things are not guaranteeing delivery, but they play an important role.

[e12e]

Google is particularly insidious: gmail will happily throw away email (not just mark as spam) to "new" recipients, while your own account, which will usually already have a "relationship" with your domain, might receive email just fine.

I just recently had an issue where I tried to send an email to a someone I'd just met. The cc-part that went to my gmail-account got through fine. He didn't even receive spam. After I set up spf, I successfully sent an email to the exact same gmail address.

If gmail had rejected the mail, there'd be no problem -- then I'd know that I'd have to take action. Quietly eating the mail... not cool.

I wonder how long until the only way to send email into gmail/outlook is to set up routing rules that send email to gmail/outlook addresses by logging in to those respective services, and sending directly, bypassing traditional unauthenticated smtp... presumably setting up one "major" delivery would be enough, as gmail can't ignore outlook.com and vice-versa...

[spotman]

Yes but you can't start from scratch without them and do a moderate amount of traffic.

If you have the same clean ips from pre dkim/domainkeys days then don't lose them, or it may be an uphill battle which I would be surprised if you didn't engage dkim to aid in fighting at that point.