Troubleshooting the simple stuff

I was talking with one of my Barry pals recently and was treated to a rant regarding deliverability experts that can’t manage simple things. We’ve been having an ongoing conversation recently about the utterly stupid and annoying questions some senders ask. Last week, I was ranting about a delivery person asking what “5.7.1. Too many receipts this session” meant. This morning I got an IM.

Barry: I see your “too many recipients” and raise you a “DNS failure.”

Me: You’re joking.

Barry: “Unknown address error (‘550’, [‘REQUESTED ACTION NOT TAKEN: DNS FAILURE’])

Me: That seems pretty self explanatory. I would close the ticket with a “not a mail issue.”

Barry: It wasn’t a ticket. It was a direct mail to me by a very well known person on the sender side. You’d die if you knew who it was. But he didn’t send me anything useful, not even an IP address.

Me: You’re kidding? Please tell me you’re kidding. Please.

This is yet another example of people bothering Barry with questions that should be answerable by anyone who holds themselves up as a delivery expert. Really.
Barry is not your free consultant. Barry has a job and it does not involve troubleshooting problems on your end. Asking questions about stupid stuff like “too many recipients this session” or “DNS failure” is why most Barry’s don’t hand out their info to senders. They don’t want to be bothered with questions just because the sender is too stupid or lazy to do their own troubleshooting.
There are two things that come to mind immediately when I see this error message and two things that I would check before even considering contacting someone.

  1. This is an internal DNS failure and the MX lookup on the sender’s side failed. The sender should do a manual DNS lookup and confirm they can get a MX record (or A) record for the recipient domain.
  2. This is a DNS failure on the receivers side. A little harder to troubleshoot, but some ISPs check the DNS of the sending domain before accepting mail. Make sure that the domain exists in DNS and is answering queries promptly.

Once you have checked DNS and everything is OK you can move to the next step. Open up a telnet session to the mail server and do a manual SMTP session. Use the same Mail From: and Rcpt To: that generated the 550 you’re attempting to troubleshoot. You don’t need to do the whole session, just through Mail From: and Rcpt To:.
If the Mail From and Rcpt To: addresses are accepted by the receiver mail server, then go back into your MTA and resend the message that originally failed.
It works, you’re done. If not, go back and think about what else might cause a DNS failure, then test it. Same as you did above. Repeat.
EDIT: While writing the post, I heard back from Barry. The problem was that the sending domain did not exist in DNS. This issue would have been identified at the 2nd DNS check. No mail to Barry needed.

Related Posts

How NOT to get your mail unblocked

My friend Barry™ contacted me earlier this week to rant about senders contacting him asking for blocks to be lifted.

Read More

What is an email address? (part two)

Yesterday I talked about the technical definitions of an email address. Eventually on Monday I’m going to talk about some useful day-to-day rules about email address acquisition and analysis, but first I’m going to take a detour into tagging or mailboxing email addresses.
Tagging an email address is something the owner of an email address can do to make it easier to handle incoming email. It works by adding an extra word to the local part of the email address separated by a special character, such as “+”, “=” or “-“. So, if my email address is steve@example.com, and I’m signing up for the MAAWG mailing lists I can sign up with the email address steve+maawg@example.com. When mail is sent to steve+maawg@example.com it will be delivered to my steve@example.com mailbox, but I’ll know that it’s mail from MAAWG. I can use that tag to whitelist that mail, to filter it to it’s own mailbox and a bunch of other useful things.
In some ways this is similar to recent disposable email address services, but rather than being a third party service it’s something that’s been built in to many mailservers for well over a decade. It doesn’t require me to create each new address at a web page, instead I can make tags up on the fly. And it works at my regular mail domain.
If you’re an ESP it can be interesting to look for tagged addresses in uploaded lists. If it’s a list owned by Kraft and you see the email address steve+gevalia@example.com in the list, that’s a strong sign that that email address at least was really volunteered to the list owner. If you see the email address steve+microsoft@example.com then it’s a strong sign that it wasn’t, and you might want to look harder at where the list came from.
One reason that this is relevant to email address capture is that tagged addresses are something that you should expect people, especially more sophisticated users of email, to use to sign up to mailing lists and that they’re something you don’t want to discourage. Yet many web signup forms forbid entering email addresses with a “+” or, worse, have bugs in them that map a “+” sign in the email address to a space – leading to the signup failing at best, or the wrong email address being added to the list at worst. This really annoys people who use tagged addresses to help manage their email, and they’re often exactly the sort of tech-savvy people who make a lot of online purchases you want to have on your lists.
More on Monday.

Read More

Comcast rate limiting

Russell from Port25 posted a comment on my earlier post about changes at Comcast.

Read More