DMARC checker

Start with the bounce text or the folder the message landed in. A permanent refusal, a temporary deferral, a broken DNS record, and a spam placement are four different jobs.

Start with the bounce text or the folder the message landed in. A permanent refusal, a temporary deferral, a broken DNS record, and a spam placement are four different jobs. Changing the template does not repair any of them.

What the mailbox is actually saying

Read the bounce or the rejection text before you change a template. A 550 is a permanent refusal. A 421 is a temporary deferral. SPF, DKIM, and DMARC failures name a DNS problem. 'Spam' in a folder is a reputation problem, and it is not the same job as a syntax error in a record.

For mail to Gmail at bulk volume, Google publishes the sender guidelines: SPF or DKIM on every message, and SPF, DKIM, and DMARC together once you are over 5,000 messages a day to Gmail, plus a spam rate that stays under 0.10% and never reaches 0.30%. Those are Google's rules, not a benchmark from a blog.

A short order of work

Each line is a different repair. Doing all of them at once means you will not know which one fixed it.

Do the first repair, then the small test. If you change the record, the list, and the template together, you will not know which one the mailbox accepted.

• Copy the bounce or the deferral text and keep it with the send.
• Suppress hard bounces. Pause the slice that drew the complaints.
• Fix the DNS record that the rejection named, then send a small authenticated test.
• Warm the mailbox you intend to keep before you raise the cold volume. A new domain with the same list repeats the problem.

What to change, and what to leave

Fix the record that failed, suppress the addresses that hard-bounced, and pause the slice that drew the complaints. Buying a new domain while the list and the template stay the same moves the symptom. Warm the mailbox you intend to keep, with mail people asked for or already know you for, before you raise the cold volume.

Do not treat open rate as proof the mail landed. Apple and other privacy changes broke that number. Replies, bounces, and complaints are the figures you can stand behind.

Read the failure in the order it happened

DNS first if the rejection names SPF, DKIM, or DMARC. The list next if the addresses are bouncing or the complaints are climbing. The template last, and only after a small send to people who already know you still lands.

Google's sender guidelines are the reference for bulk mail to Gmail: authenticate, keep the spam rate under 0.10% and never at 0.30%, and give people a one-click way to stop. Microsoft and Yahoo publish their own. A number from a thread is not a target for your domain.

Leave the template until the mailbox is quiet

A repaired record or a cleaned list should show up in the next small send, to people who already know you. If that send still fails, the template was never the problem, and another draft will not make it one.

Keep the bounce text with the send. The next time the same refusal appears, you already know which repair it was, and you do not have to start the argument from the top.