When an email address stops working
If mail to a customer comes back undelivered, RadiusOS marks it on their record and stops sending there. This is what keeps a stale list from quietly wrecking the rest of your email.
What you'll see
On the customer's record, in red: This email address doesn't work, with the reason and the date. On your list, their address is struck through with a small icon next to it.
You do not have to go looking. The point of putting it on the record is that you find out the moment you open them, rather than from a group email report weeks later.
Why it matters more than it sounds
Every mail provider watches how often you send to addresses that do not exist. It is one of the clearest signals that someone is working from a bought or stale list, and the penalty is not limited to those addresses. Your whole domain gets treated as less trustworthy, which means the estimate you send tomorrow is more likely to land in spam.
So the moment an address is confirmed dead, RadiusOS stops sending to it. Anything already queued for that person in a running campaign is cancelled too.
The two kinds of failure
| What happened | What RadiusOS does |
|---|---|
| The address doesn't exist, or the account was closed | Stops immediately. One failure is enough; the address is not coming back. |
| Their mailbox is full, or their server was down | Keeps trying. Only stops after three failures in a row, so someone on holiday with a full inbox is not written off. |
A successful delivery clears the count, so an address that has trouble occasionally and then works again is never retired for it.
Fixing it
Open the customer
The red banner names the address and the reason.
Correct the address
Usually it is a typo, or they have left the company. Edit the email field as normal.
Clear the flag
Press Clear on the banner. The next follow-up or group email will include them again.
If you think the bounce was wrong, clear it without changing anything. The next send tries again, and if it bounces once more the flag comes back.
How this differs from unsubscribing
Both stop automatic emails, and they are shown separately on purpose because the right response is opposite.
A bounce is a fact about an address. Fix the address and it goes away. An unsubscribe is a decision by a person, and clearing it is something you should only do when they have actually asked you to start again. Correcting a typo never clears an unsubscribe.
Neither one stops you replying to somebody directly about work in progress. They apply to follow-ups and group emails.
Where the information comes from
When a message cannot be delivered, the receiving mail server sends a notice back to your inbox. RadiusOS reads those notices, works out which address failed and why, and puts it on the right record. It checks before every batch of sending, so a bounce partway through a campaign stops the rest of that campaign rather than being noticed afterwards.
This needs Gmail connected, since the notices arrive in your mailbox.