A temporary refusal is not a dead list

Answer A temporary refusal is not a dead list. RFC 6647 describes greylisting, the practice of giving an unknown mail client degraded service for a while, often by answering with a temporary SMTP failure. The delay is measured in minutes or a small number of hours. A solo ad platform that tries once and quits will call that delay a failure. Ask whether yours retries.

The note that started this: RFC 6647, Email Greylisting, RFC 6647.

Buyers see a red count and assume the addresses were bad. Sometimes they were. Sometimes the receiving server did not know the sending client yet and asked it to come back, which is the whole trick. Simplistic unwanted mail often does not come back. A normal mail server does. If you buy solo ads from a tool that does not behave like a normal mail server, you will pay for a list that looks worse than it is, or you will miss the mail that would have landed on the second knock.

The document is from 2012, and the behavior is older than the document. It is not a June product announcement. The useful part is the shape. Greylisting is early and cheap. It is aimed at traffic that sprays and leaves. It is not a person clicking spam, and it is not a verdict on the copy. The RFC recommends basing the decision on a tuple of the IP address, the envelope sender, and the first recipient. A different IP, or a different envelope, can look like a new stranger even when the creative is the same.

What is greylisting on a solo ad?

RFC 6647 describes it as temporarily degraded service for an unknown or suspect source, often a temporary SMTP failure, over minutes or a small number of hours. It is not a permanent rejection and it is not a spam click.

Temporary means the server is willing to talk again. Permanent means it is not. Those are different reply codes, and they ask for different behavior. A seller who folds both into bounced has thrown away the distinction the mailbox was careful to make. You cannot audit a send whose report has one word for two outcomes.

There is also a confusion the RFC itself names. Not every temporary failure is greylisting. A server can say try later because it is busy, because a disk is full, or because a policy asked for a delay. The buyer does not have to diagnose which temporary it was. The buyer has to know that temporary is an instruction to retry, and that a platform which ignores the instruction is not finishing the send.

• Temporary failures are a separate line from hard bounces.
• The platform retries them.
• The retry window is something a person can say out loud.
• A one-shot tool is named as a one-shot tool before you pay.

Why does a single attempt make a list look dead?

A mailbox that greylists expects the sending server to retry. A tool that tries once and gives up records a failure. The address may have been willing to take the mail on the next try.

This shows up on cheap sending rigs and on laptop sprays. They open a connection, take the first no, and move on, because retrying is work and a queue is a machine they did not build. The report then fills with failures that a patient server would have cleared. The buyer is told the list is tired. The list may have been behind a door that opens on the second knock.

The reverse mistake is also for sale. A seller retries for days, long after any reasonable greylist window, and calls the eventual acceptance proof that the first refusal did not matter. A multi-day delay is not the mechanism in this document. Ask for the window. Minutes or a small number of hours is the range the RFC uses. A week is a different story, and it may mean the mail is no longer the mail you approved.

What should you ask a seller about temporary failures?

Ask whether the platform retries temporary failures, ask how long it keeps trying, and ask for those retries to be counted apart from hard bounces.

Three facts. A yes on retry. A duration. A split in the report. If they cannot answer, the delivered number is whatever the first attempt felt like. Safe solo ads sellers can tell a delay from a dead address because their platform can.

Do not let a greylist story become an excuse for every failure either. A hard bounce is still a hard bounce. A complaint is still a complaint. Greylisting explains one temporary pattern. It does not launder a bought file. On the second day of the month, split the red numbers before you believe any of them.