> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stardex.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Email deliverability : Best Practices

> Protect your sending reputation with domain authentication, sensible sending volume, and outreach best practices.

Good deliverability means your emails actually land in inboxes, not spam folders. This guide covers how Stardex sends emails, what impacts deliverability, and how to get the best results from your outreach campaigns.

***

## How Stardex Sends Emails

When you connect your Gmail or Outlook account to Stardex, you grant us OAuth permission to send emails on your behalf. This means **Gmail (or Outlook) is the actual sender** — we simply tell it when to send and to whom. Your emails go out from your real inbox, show up in your sent folder, and replies come back to you directly.

This is different from tools that use their own SMTP servers to send emails. With SMTP-based sending, emails are routed through a third-party server, which mailbox providers can flag as suspicious — especially if unsubscribe headers or proper authentication aren't included. Because Stardex sends through your actual mailbox, your emails are treated the same as if you hit send yourself in Gmail.

Mailbox health for a connected address lives under **Settings → Email & other integrations → Mailboxes → Sending**.

<Note>
  Stardex is built for low-volume, high-quality outreach — the kind that executive search firms and recruiters do daily. If you need to send more than a few hundred emails a day from a single inbox, we recommend dedicated cold email tools like Instantly or Smartlead which are built for that scale.
</Note>

***

## What Impacts Deliverability

Even though Stardex sends through your real inbox, deliverability still depends on a few key factors.

### 1. Domain Authentication (SPF, DKIM, DMARC)

These are DNS records that prove your domain is legitimate. Gmail, Outlook, and Yahoo now strictly enforce these — emails that fail authentication checks get rejected outright, not just sent to spam.

Most Google Workspace and Microsoft 365 accounts have SPF and DKIM configured by default. DMARC you may need to set up manually. Ask your IT admin or domain provider to confirm all three are in place.

**Quick check:** Use [mail-tester.com](https://www.mail-tester.com/) to send a test email and see if your authentication is set up correctly. If something's off, it'll tell you exactly what to fix.

### 2. Sending Volume

This is the biggest factor you can actually control. Gmail and Outlook track how many emails you send per day, and if you send too many too fast, their spam filters kick in — regardless of how the email was sent.

**Recommended daily limits based on domain age:**

| Domain Age | Recommended Max Emails/Day |
| - | - |
| Less than 3 months | 15–25 |
| 3–12 months | 25–50 |
| 1–3 years | 50–100 |
| 3+ years (established) | 100–300 |

These are per inbox. If you're just getting started with a new domain, keep it low and ramp up gradually over a few weeks. If your firm has been around for 5–10 years and your domain has solid history, you have more room — but we still wouldn't recommend pushing past 200–300/day from a single inbox.

<Note>
  These limits include all emails from your inbox — campaigns, follow-ups, and regular day-to-day emails. Keep that in mind when planning your outreach volume.
</Note>

### 3. Sending Patterns

Sending 80 emails at 9:00 AM sharp looks like a bot. Sending 80 emails spread across the morning looks like a human. Mailbox providers notice the difference.

Stardex helps here by:

* **Drip sending** bulk enrollments roughly every 15-30 seconds randomly rather than all at once
* **Spreading scheduled sends** across a few minutes when you enroll a large batch at the same time
* **Limiting bulk enrollments to 50 at a time** to protect your sending reputation

If you're scheduling multiple campaigns for the same send time, stagger them by at least 5–10 minutes.

### 4. Spam Complaint Rate

If recipients mark your emails as spam, it directly hurts your sender reputation. Gmail wants you below 0.1% (1 complaint per 1,000 emails). Go above 0.3% and your emails will start getting filtered or rejected.

The best way to keep complaints low: send relevant, personalized emails to people who would reasonably expect to hear from you. This is where Stardex's AI personalization variables help — even a short personalized line makes a difference.

### 5. Bounce Rate

Sending to invalid or outdated email addresses damages your reputation. Use Stardex's "Find Emails" feature to verify addresses before sending, and keep an eye on bounced emails in your campaign dashboard. If you're seeing bounce rates above 5%, clean your list before sending more.

### 6. Content Quality

A few things that can trigger spam filters:

* Excessive links in the email body
* Spammy language ("act now", "limited time", "guaranteed")
* Large images with very little text
* Sending the exact same copy to hundreds of people with zero personalization

Keep emails short, conversational, and relevant. Write like you're emailing one person, not blasting a list.

***

## A Note on Open and Link Tracking

Stardex tracks email opens and link clicks to give you campaign metrics. A few things to keep in mind:

**Open tracking is not very reliable.** Many email clients (especially Apple Mail and some corporate setups) pre-fetch images automatically, which can register as a false "open." Other clients block tracking pixels entirely, so real opens go unrecorded. Use open rates as a rough directional signal, not a precise metric.

**Link tracking** is more reliable than open tracking but can occasionally trigger spam filters if overused. If you're including links, keep it to 1–2 per email max.

**Reply rate is the most reliable metric** for understanding how your campaigns are performing. Focus on that.

***

## Tips for Maximizing Deliverability

### Connect Multiple Domains

If you're doing high-volume outreach, we recommend connecting multiple domains and spreading your sends across them. For example, if your primary domain is `yourfirm.com`, you could set up `yourfirm.co` or `mail.yourfirm.com` for outreach. This protects your primary domain's reputation and gives you more headroom on volume.

### Consider an Email Warmup Tool

Email warmup tools run in the background and generate positive engagement signals (opens, replies, moving emails out of spam) on your inbox. This builds and maintains your sender reputation over time. Tools like [MailReach](https://www.mailreach.co/) or [Warmforge](https://www.warmforge.ai/) run about \~\$20/month per inbox. Especially worth it if you're doing consistent outreach volume or working with a newer domain.

### Warm Up New Domains Gradually

If you just set up a new domain or email account, don't start sending campaigns on day one. Send regular emails for a couple of weeks, then start campaigns at low volume (10–15/day) and increase gradually over 3–4 weeks.

### Spread Your Sends Across the Week

Tuesday, Wednesday, and Thursday mornings tend to see the best engagement. Avoid sending large batches on Mondays or Fridays. Spreading your volume across multiple days is better than concentrating everything on one day.

**What to Do If Your Domain Is Already in Trouble**

If your emails are landing in spam, getting filtered, or you're seeing a sudden drop in replies, your domain reputation has likely taken a hit. Here's how to recover.

**1. Stop the bleeding**

Pause or drastically reduce sending from the affected inbox. Continuing to send while your reputation is damaged makes it worse. Cut volume to 5–10 emails/day max while you work through the rest of this list, and only send to people you actually know.

**2. Set up backup domains so your business doesn't stall**

While you're cleaning up the main domain, get 2–3 secondary domains so outreach can continue. For example, if your primary is `yourfirm.com`, register `yourfirm.co`, `getyourfirm.com`, or `mail.yourfirm.com`. Set up mailboxes on each, configure SPF/DKIM/DMARC, and warm them up before sending campaigns.

**3. Put the damaged inbox on a warmup tool**

Tools like [warmupinbox.com](https://www.warmupinbox.com/), [MailReach](https://www.mailreach.co/), or [Warmforge](https://www.warmforge.ai/) generate positive engagement signals on your inbox to rebuild reputation. Run this for at least 2–4 weeks before resuming any real outreach volume.

**4. Get friendly humans to vouch for you**

Send a few emails to colleagues, friends, or customers who know you. Ask them to:

* Reply to the email
* If it landed in spam, mark it as "not spam" and move it to inbox
* Star or flag the message

A handful of these signals from real engaged users helps Gmail and Outlook re-learn that you're legit.

**5. Recheck authentication**

Even if SPF, DKIM, and DMARC were set up before, recheck them. Sometimes records get edited, expire, or weren't fully buttoned up to begin with. Run a test through [mail-tester.com](https://www.mail-tester.com/) and fix anything that scores below a 9/10.

**6. Ramp back up slowly**

Once your warmup has been running and authentication is clean, start sending campaigns again at low volume (10–15/day) and increase gradually over 3–4 weeks. Don't jump back to your previous volume right away.

***

## What's Coming

We're working on an **org-level daily sending limit** that will make this easier. You'll be able to schedule as many emails as you want, and Stardex will automatically enforce a daily cap per inbox — if more emails are queued beyond that limit, we'll push them to the next day. This way you don't have to manually track your volume. No exact ETA yet but it's on the roadmap.

***

## Summary

| Factor | What to Do |
| - | - |
| Authentication | Confirm SPF, DKIM, DMARC are set up on your domain |
| Daily volume | Stay within recommended limits for your domain age |
| Sending pattern | Spread sends out, stagger scheduled campaigns |
| Spam complaints | Keep below 0.1%, send relevant personalized emails |
| Bounce rate | Verify emails before sending, clean your lists |
| Content | Short, personalized, minimal links |
| Warmup | Consider a warmup tool (\~\$20/mo) for consistent senders |
| Multiple domains | Spread outreach across domains for higher volume |

**Need help checking your setup?** Send a test email to [mail-tester.com](https://www.mail-tester.com/) and share the results with us — we can help you diagnose any issues.


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