[dsr_]

This is demonstrably not true.

SPF and DKIM are neither necessary for mail delivery nor sufficient to assure delivery.

There is, in fact, nothing you can do to guarantee delivery of your mail once you offer it to another mail server. If the recipient doesn't like it, it will be dropped.

You can do lots of things to help. The most important is to not be a spammer. Don't send substantially the same mail to lots of people who haven't asked for it.

[FooBarWidget]

> SPF and DKIM are neither necessary for mail delivery nor sufficient to assure delivery.

This statement, while true, is completely useless. Without SPF and DKIM email providers will view your emails with more suspicion, so that a larger percentage of your email ends up in spam even when it really isn't. SPF and DKIM do not guarantee delivery but they reduce the chance of your email being inappropriately recognized as spam.

[merb]

It's somewhat true. DKIM checks the authenticity of a email domain. So it definitly helps. SPF does barely the same. that's why you got into spam if you not set RDNS OR DKIM OR SPF. Since the other server can't be sure if the server is allowed to send mails with the provided domain.

Mailservers are simple, basically you can send with every domain available, however that won't work since other servers will handle that via SPF, RDNS or DKIM.

[slacka]

If it's demonstrably not true, why is it then that multiple reports of mail going into SPAM folder stop coming in, once I setup SPF and DKIM? While it's true that reverse DNS is probably a bigger factor. Not having these 2 setup is going to increase your odds of ending up in the SPAM mailbox.

[spc476]

I have reverse DNS and SPF, but not DKIM and I don't have that many issues getting my email delivered. I did have issues with AOL, but once I registered as the contact for my IP address with them, those issues went away. I've also had one or two issues with GMail over the years, but last I knew, it was okay (I normally don't deal with GMail addresses that much).

Then again, I've had my domain for 17 years, self hosting everything for 16 years (with the occasional IP change, but I think I've had the same IP now for almost ten years so go figure).

[thrownaway2424]

Existence of SPF and DKIM will not necessarily keep your message out of the "spam" folders, but absence of them will significantly increase the chances of being delivered there.