Best Practices on Domain Name Choices

If you're going to use your domain (or a custom domain) with an email platform, try, if at all possible, to use your main domain name.

Here's why I say that.

Another day, another dead DNSBL

Another anti-spam blacklist has ceased to exist. For more on the now-defunct Email Basura blacklist, head over to DNSBL Resource.

New XNND DNS Tool Update!

I've updated the XNND DNS lookup tool so that it you can now select "Multi DNS = yes" and the tool will now make the same DNS query against a number of different public DNS servers all in a row.

It'll help you catch issues where you've perhaps updated a DNS entry but are waiting out the TTL (DNS cache) and want to check to see what different servers can see. It can also help you identify some kinds of intermittent DNS issues. I've already run into a couple of different scenarios where I've found it quite useful. I hope you'll find it useful, too!

Example query: Look up the MX records for spamresource.com against all available DNS servers.

Sender ID is back!! No, wait...

Gossip has been flowing through the back channels lately suggesting that Microsoft might be checking Sender ID email authentication DNS records anew.

No...but. My answer to this is a little nuanced, so bear with me.

Dead email domain: ono.com

It appears that the email domain ono.com is going away. ONO was a Spanish broadband communication and entertainment company, purchased by Vodafone in 2014. Fast forward to 2019, and it looks like Vodafone is shutting down the ono.com email domain.

How not to get people to open your emails

Email Compliance manager Skyler Holobach explains why you shouldn't act on clickbait advice you find on the internet.  Read more >>

Charter/Roadrunner bounces?

I'm pulling together information from various sources here, and using a bit of guess work. So keep in mind that this info is not guaranteed.

When sending mail to Charter/TWC/RoadRunner domains (full list here), are you seeing any of these bounces?

How Email Spam Filters Work Based On Algorithms

This is pretty basic stuff; it's not inaccurate, but it's not complete. Most other ISPs have other things going on that can also result in emails going to the spam folder. But as a starting point? It's not too bad. Check it out, from NBC: How Email Spam Filters Work Based On Algorithms.

Need example SMTP bounces for different ISPs?

Wondering what different kind of bounces an ISP might give to you? Postmark put together this handy-dandy SMTP bounce example lookup tool. It's called the SMTP Field Manual and it's pretty neat.

Spamhaus Blacklist Changes

Speaking of Spamhaus, this just popped up in my RSS feed reader. It looks like Spamhaus is going to take a harder stance against users who query their blacklists via open or public DNS systems (such as Google Public DNS or Cloudflare's 1.1.1.1 Service). They're going to respond to all queries from public/open DNS systems with a new 127.255.255.254 answer code, and respond to excessive queries from other sources with a new 127.255.255.255 response code. The net here is that if you query Spamhaus a lot, and aren't a registered, paying user, or if you use public DNS services for even your small hobbyist server, you're going to get cut off.

And based on the way this is implemented, it's possible that a bunch of legitimate mail will start bouncing before all Spamhaus users figure it out.

Even on my own hobbyist Linux box, I'm likely to run afoul of this. Instead of running my own DNS server, I just use Google's public DNS, and I use Spamhaus's "Zen" blacklist in my Postfix email server. Or at least I did, until I removed that DNSBL from the mail server configuration just now.

Stay tuned. I bet we're going to start seeing people popping up to ask why they're suddenly not receiving any more inbound mail.

Click here to head on over to Spamhaus to read the announcement.