Key takeaways
- Delivered is not the same as in the inbox: a server can accept mail and still file it as spam.
- SPF, DKIM and DMARC prove the mail really comes from your domain.
- Sender reputation is earned slowly and lost quickly, mostly through bounces and complaints.
- Clean lists and relevant, modest sending matter more than any wording trick.
Delivery, deliverability and inbox placement
Delivery means the receiving server accepted the email, while deliverability, or inbox placement, is where it then lands. An email can be delivered and still sit in spam, where it is as good as unsent.
Mailbox providers decide placement for each message, using signals about the sender, the content and how recipients have treated similar mail before. Nobody outside the provider sees the full set of rules, so good practice is about sending mail that looks and behaves like mail people want.
SPF, DKIM and DMARC explained
SPF, DKIM and DMARC are three DNS records that let receiving servers check an email really comes from the domain it claims. Missing or broken authentication is one of the quickest ways to land in spam.
- SPF lists the servers allowed to send mail for your domain.
- DKIM adds a signature that shows the message was not altered on the way.
- DMARC tells receivers what to do when SPF or DKIM fail, and sends you reports.
How sender reputation is built and lost
Sender reputation is built by sending wanted mail consistently over time, and lost through bounces, spam complaints and sudden jumps in volume. Mailbox providers track it for your domain and, to a degree, for each mailbox.
Replies, messages moved out of spam and steady volumes help. Hard bounces from bad addresses, hits on spam traps (old or planted addresses that no real person uses) and many recipients marking mail as spam hurt. A brand new domain has no history at all, so it needs a gradual start.
How to avoid spam filters in cold outreach
To avoid spam filters in cold outreach, send fewer, more relevant emails to addresses you have reason to trust. Filters respond to how recipients react, so the best defence is mail people do not mind receiving.
- Verify addresses before sending, and treat catch-all domains with care.
- Send from a real, authenticated mailbox at a steady, modest volume.
- Write a short, specific message to one person, in plain text with few links.
- Make it easy to opt out, and honour opt-outs at once.
- Stop sending to an address after a hard bounce.
What Pebbles Ai does and does not do for deliverability
Pebbles Ai offers no deliverability tooling: it does not warm up mailboxes, rotate senders, test inbox placement or monitor reputation. Domain authentication and sending volumes stay with you and your email provider.
What it does is narrower. Smartbox works with your own connected Gmail or Outlook mailboxes, and work emails from Find fresh leads carry a confidence score and a catch-all flag, which you can use when deciding which addresses to check before sending.
Where Pebbles Ai fits
- CapabilityProspecting & customer recordsWork emails found by Find fresh leads carry a confidence score and a catch-all flag, so you can decide which addresses to verify before you send.
- CapabilitySmartboxSmartbox works with your own connected Gmail or Outlook mailboxes, so mail goes out from an account you already control. It does not warm up mailboxes or monitor reputation.
Common questions
How can I check my sender reputation?
Use your mailbox provider's postmaster tools, read your DMARC reports and check whether your domain appears on public blocklists. Rising bounces or complaints are an early warning.
Does a new domain need time before sending cold email?
Usually, yes. A domain with no sending history is treated with caution, so start with low, steady volumes of wanted mail and increase gradually.
Can Pebbles Ai improve my email deliverability?
No. Pebbles Ai offers no warm-up, inbox placement testing or reputation monitoring. It helps you write and send from your own mailbox, and deliverability stays with your domain set-up and sending habits.
What is a spam trap?
An email address that no real person uses, kept or recycled by mailbox providers and blocklist operators to catch senders with poor list hygiene. Sending to one harms your reputation.
About this page. Written by the Pebbles Ai team for people who run sales, marketing and growth. Last updated .
