Showing posts with the label RFCs

From DMARCbis to DMARC: New DMARC RFCs

DMARC has been updated! Three new RFCs have been published (RFCs 9989 , 9990 , and 9991 ) governing the latest incremental updates to the DMARC standard. TL;DR? It's all about the DNS tree walk, privacy concerns around failure reporting, and removing little used flags (PCT, RI, and RF). Open question: How quickly will mailbox providers implement support for this incremented spec? We shal…
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Help! Domain of sender address does not resolve!

Are you trying to send email and seeing it rejected with "Domain of sender address does not resolve" or "Unresolvable RFC.5321 or RFC.5322 from domain"? These SMTP rejections are telling you that something is missing from your DNS. Microsoft , Yahoo and oth…

DELIVTERMS: Simple Mail Transfer Protocol (SMTP)

Simple Mail Transfer Protocol (SMTP) is the lingua franca used by mail servers to communicate with each other, in the process of sending and receiving email messages. Here's a greatly oversimplified bullet-point explanation of how the email sending and receiving process wo…

Gmail: More RFC 5322 bounces coming-- helping to impede DKIM replay attacks

A few days ago, Google started notifying (some) Google Workspace customers of updated spam filter/blocking changes coming to the Gmail email service. They're moving to more proactively block emails that have headers violating RFC 5322, and it is believed that this is an att…

Gmail: Weird RFC 5322 bounces and what to do about them

Here is the scenario. Maybe you've just gotten a bounce message that looks like this: Aug 25 11:20:24 s1 postfix/smtp[26906]: 98299221BB: to=<x@gmail.com>, relay=gmail-smtp-in.l.google.com[142.250.141.27]:25, delay=1.2, delays=0.04/0.77/0.2/0.21, dsn=5.7.1, status=bou…

I love RFC 8058 and you should, too

Last week I talked about one-click unsubscribe and why I don't think it's a great process. Basically, my concern is bot clicks. I've seen it happen too many times -- email security software will scan an email message body and follow all the links in the message. Th…

DELIVTERMS: Friendly From

The Friendly From is not quite its own separate header, but it is a field in your from header. It is the text that goes next to your email address in the from header. If the from address header in my email looks like this: From: Al Iverson <aiversontestmail@wombatmail.com&g…

Blocking emails to role accounts: Best practice?

Do you block email signup attempts from role accounts? If not, I think you should consider it. What's a role account, you might ask? It's an email that has a username part (the part to the left of the @ sign) that is commonly reserved for either a system function or a…

Characters in the local part of an email address

Need a "common sense" breakdown showing you what characters should be allowed in the username part (local part) of an email address? This handy guide from Jochen Topf covers exactly that. It doesn't EXACTLY align with RFCs, but when you look at it from a common …