Email deliverability basics: warm-up, pace and avoiding spam

You can have the right list and a well-written email, and still get nowhere if your message lands in spam. Email deliverability is simply whether your email reaches the inbox rather than the spam folder. It isn't controlled by one setting. It comes from a handful of habits: how you warm up a mailbox, how fast you send, what you write, who you send to and how your domain is set up.

This guide covers those basics in plain terms, then shows how to apply them when you send campaigns from Signalsant.

What decides where your email lands#

Mailbox providers such as Gmail and Microsoft decide, message by message, whether to deliver to the inbox, to spam, or not at all. They don't publish their exact rules, but the broad signals are well known:

• Your sending reputation. A mailbox and domain with a history of normal, wanted email are trusted more than a brand-new one that suddenly sends a lot.
• Your sending pattern. Steady volume spread through the day looks like a person. A sudden burst looks like a bulk sender.
• Your content. Plain, personal emails look like one-to-one mail. Heavy designs, lots of links and attachments look like marketing.
• Your list. Sending to addresses that bounce tells providers you don't know who you're writing to.
• Your domain setup. Authentication records prove that mail claiming to be from your domain really is.
• How people react. Emails that recipients mark as spam hurt you; relevant emails people actually want help you.

You can't control the provider's decision, but you can control every item on that list.

Warm up a new mailbox slowly#

A new mailbox, or one that has only ever sent a few emails a day, has little reputation either way. If it suddenly sends a large batch of cold email, providers have every reason to be suspicious.

Warming up means starting small and raising volume gradually:

• Start low. Send to a small number of companies a day for the first weeks.
• Raise it in steps. Increase the daily volume over a few weeks, not overnight.
• Watch for trouble. If test emails start landing in spam or more messages fail, hold the pace or lower it for a while.
• Spread the load. If you need more volume, use several mailboxes rather than pushing one hard.

There is no single correct schedule. The safe rule is that volume should grow gradually, and that you should never jump from almost nothing to a lot.

Keep a steady sending pace#

Even a well-established mailbox should not send a whole campaign at once. Real people send email during their working day, a few at a time. Aim for the same pattern:

• Send during working hours in your recipients' timezone, not yours.
• Space emails out across that window instead of sending them in a burst.
• Keep the daily volume consistent. Big swings from one day to the next look unnatural.

Write like a person#

For cold outreach, the email that looks least like marketing usually does best.

• Use plain text, one-to-one in tone. Write as you would to a single person you have a reason to contact.
• Keep images, links and attachments to a minimum. One link, or none, is plenty for a first email.
• Personalise properly. Use the company's name, city or category so the email is clearly for them. Make sure missing details never leave a blank gap.
• Write a subject line that matches the email. Misleading subjects annoy recipients and invite spam reports.
• Vary your wording. Rotating two or three versions of an email is better than sending identical text to everyone.
• Include an easy way to opt out. A short line such as "Reply 'no thanks' and I won't email again" is enough, as long as you honour it.

Send only to good addresses#

Bounces are one of the clearest signs of a poor list. Every email to an address that doesn't exist tells providers you aren't careful about who you contact.

• Build your list from businesses that publish an email address.
• Check addresses before you send, and skip any that would bounce.
• Be cautious with domains that accept every address, because you can't confirm the person is there.

Set up SPF, DKIM and DMARC#

These three DNS records tell receiving servers that mail from your domain is genuine:

• SPF lists the servers allowed to send mail for your domain.
• DKIM adds a signature that proves a message wasn't altered and really came from your domain.
• DMARC tells receivers what to do with mail that fails those checks, and where to send reports.

You don't need to be technical to get this done. Ask whoever manages your domain to check that all three are set up for the mailbox you send from. Google Workspace and Microsoft 365 both publish guides for it.

Don't contact the same company too often#

Repeated emails from the same sender to someone who hasn't replied are a quick route to spam reports. Contact each company once per campaign unless you have a good reason, and avoid putting the same companies into several campaigns at the same time.

Email deliverability, step by step with Signalsant#

Signalsant sends campaign email from your own Gmail, Microsoft 365, Outlook.com or SMTP mailbox, so your mailbox and domain reputation are what count. Here is how to apply the basics above as you go from search to launch.

1. Find companies with a Deep Search. Open Companies → Deep search, click New deep search, enter a Query, Country and State, optionally a City, and click Start search. Start with one city while you test.
2. Let enrichment run. Emails come from each company's own website and fill in automatically after the search. Each address gets a badge such as Verified, Deliverable, Catch-all, Undeliverable or Unverified, and every address is checked before a campaign email goes to it.
3. Build a group from companies with an email. On Companies, search for something like "plumbers in Leeds with an email", tick the results and click Add to group, or use Create group on a finished Deep Search. The group page shows how many companies have a sendable email.
4. Test your mailbox. In Integrations, open the mailbox and use the Test tab: Test connection, then Send test email to an address you can check, including its spam folder. See Test a mailbox integration.
5. Write plain content. In the campaign's Content step, start from a plain template. The Personal note starter is plain text, reads like a one-to-one email, and is the starter recommended for cold outreach deliverability. Give every variable a fallback, such as {{contact.first_name | "there"}}, and use Add another email to rotate two or three versions. If you use AI to draft or write emails, read the results before they go out.
6. Set the pace. In Sending → Pace, choose Companies a day. Presets are 25, 50, 100 and 200, and Custom allows any number from 1 to 5,000. With a new mailbox, start at 25 or 50 and raise it over a few weeks. Signalsant warns you above 200 a day from one mailbox, because that "risks the spam folder".
7. Set sending hours. Switch on Only send during these hours, pick your recipients' Timezone, and set From and Until. Each day's emails are spaced evenly across that window. If the switch is off, emails go out between 09:00 and 17:00 UTC.
8. Leave resends off. Keep Allow resends off unless you have a reason, so each company is contacted once.
9. Review and launch. On Review & launch, fix anything flagged and click Send me a test to see the email in a real inbox (it's offered when your first email comes from your template library). Then click Launch campaign.

The details are in Improve deliverability and Sending pace and schedule.

How Signalsant keeps the pace steady#

A few things happen for you once a campaign is running:

• Daily plans, not bursts. Each day, Signalsant plans emails to up to Companies a day companies when your sending hours begin, and spreads them across the window. A day never gets more than the limit.
• No catch-up bursts after a pause. If you pause and resume, any backlog is spread across the following days.
• Undeliverable addresses are skipped. They don't count towards your daily limit and show under Skipped (undeliverable) on the Schedule tab.
• A gap between automatic rounds. If you do turn on Allow resends, a new round starts by itself only after every email from the previous round has gone out and at least 7 days have passed.

What to watch after launch#

Signalsant measures delivery: whether your mail provider accepted each message. It doesn't track opens, clicks or replies, so read replies in your own mailbox.

Keep an eye on:

• Failed messages. Check the Failed tab in the Outbox for the reason. A run of failures is a sign to slow down and check your mailbox.
• Your own test emails. If a test lands in spam, look again at your content, your pace and your domain records before raising volume.
• Mailbox access. If Google or Microsoft revokes access, for example after a password change, the campaign shows Auto-paused until you reconnect the same mailbox. Planned emails stay planned.

Stay on the right side of the rules#

Deliverability and compliance go together: emails people want rarely get reported as spam. Rules differ by country, such as CAN-SPAM in the US and GDPR and PECR in the UK and EU. This isn't legal advice, but in general:

• contact businesses with a genuine reason to hear from you;
• be honest about who you are and why you're writing;
• include your own opt-out line, because Signalsant doesn't add an unsubscribe link automatically;
• stop emailing anyone who asks you to.

Send your first campaign the careful way#

Signalsant is free during early access. Find your market with a Deep Search, start at a gentle pace and build from there.

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