How to Add a Custom Domain in SendGrid

You spent hours crafting the perfect cold email. Compelling subject line. Tight copy. Strong call to action.

Then it lands in the spam folder.

Sound familiar? The problem usually isn’t your message — it’s your sender infrastructure. And one of the most overlooked fixes is also one of the simplest: setting up a custom domain in SendGrid.

This guide walks you through exactly how to do it, why it matters more than most people realize, and how to verify everything is working before you send another campaign.

Why a Custom Domain Actually Matters

Before diving into steps, it’s worth understanding what’s at stake.

Email deliverability is a numbers game — and most people are losing it.

• 45% of all email sent globally is spam, according to Statista. ISPs are increasingly aggressive about filtering anything that looks suspicious.
• Emails authenticated with a custom domain see up to 10% higher inbox placement rates compared to those sent from shared IP pools using generic sending domains.
• According to SendGrid’s own research, authenticated domains reduce spam complaints by as much as 68%.
• 73% of B2B marketers say email is their primary channel for lead generation — meaning your deliverability directly impacts revenue.
• Domain-based authentication (SPF, DKIM, DMARC) is now a hard requirement for bulk senders to Gmail and Yahoo as of 2024, affecting anyone sending more than 5,000 emails per day.
• Organizations that implement proper email authentication see inbox rates of 85–95% versus 55–65% for unauthenticated senders.
• Domain reputation accounts for roughly 83% of an email’s chance of reaching the inbox, according to Return Path data — far outweighing content quality.

In plain terms: without a custom domain properly configured in SendGrid, you are fighting deliverability with one hand tied behind your back.

What You Need Before You Start

Setting up a custom domain in SendGrid requires a few things in place:

• A SendGrid account (free tier works, but Essentials or higher is recommended for business sending)
• A domain you own (e.g., yourcompany.com) — this should ideally be a subdomain like mail.yourcompany.com or send.yourcompany.com to protect your root domain’s reputation
• Access to your DNS provider (GoDaddy, Cloudflare, Namecheap, Route 53, Google Domains, etc.)
• Basic familiarity with DNS records — you’ll be adding CNAME records, so knowing what that means helps

Pro tip: Always use a subdomain for sending, never your root domain directly. If that subdomain gets flagged, your root domain — and its web traffic, business email, and brand reputation — stays protected.

How to Add a Custom Domain in SendGrid

Step 1 — Log Into Your SendGrid Account

Go to app.sendgrid.com and sign in. Navigate to Settings in the left sidebar.

Step 2 — Open Sender Authentication

Under Settings, click Sender Authentication. This is the central hub for all domain and email address verification in SendGrid.

You’ll see two options:

• Domain Authentication — verifies the domain you’re sending from
• Link Branding — customizes the tracking links in your emails

Start with Domain Authentication.

Step 3 — Click “Authenticate Your Domain”

Click the blue “Authenticate Your Domain” button. SendGrid will walk you through a setup wizard.

Step 4 — Choose Your DNS Host

SendGrid will ask which DNS provider you use. Select yours from the dropdown. If it isn’t listed, select “Other”.

Why does this matter? SendGrid tailors its instructions and sometimes the DNS record format based on your provider. Cloudflare, for instance, handles CNAME records slightly differently than GoDaddy.

Step 5 — Enter Your Domain

Type in the domain you want to authenticate. As mentioned above, use a subdomain — for example:

mail.yourcompany.com

or

em.yourcompany.com

Check “Use automated security” if you want SendGrid to automatically rotate your DKIM keys. This is recommended. Leave the “Use custom return path” option checked as well.

Click Next.

Step 6 — Copy the DNS Records SendGrid Provides

SendGrid will generate 3 CNAME records you need to add to your DNS provider. They’ll look something like this:

Copy these exactly. A single character error will break authentication.

Step 7 — Add the DNS Records at Your Provider

Log into your DNS provider and navigate to your domain’s DNS management panel.

For Cloudflare:

• Go to your domain > DNS > Add Record
• Set Type to CNAME
• Paste the Name and Target (Value) fields
• Set Proxy status to DNS only (grey cloud, not orange) — proxied CNAME records break SendGrid authentication

For GoDaddy:

• Go to My Domains > DNS Management
• Add Record > CNAME
• Paste the Host (Name) and Points To (Value) fields

For Namecheap:

• Domain List > Manage > Advanced DNS
• Add New Record > CNAME Record
• Paste the Host and Value

Important: Most DNS providers auto-append your root domain to the subdomain field. If your record name shows as em1234.mail.yourcompany.com.yourcompany.com after saving, you’ve entered the full hostname — remove the root domain from the field and enter only the subdomain portion.

Step 8 — Wait for DNS Propagation

DNS changes don’t take effect instantly. Propagation typically takes anywhere from a few minutes to 48 hours, though most providers propagate within 15–30 minutes for CNAME records.

You can check propagation status using tools like:

• whatsmydns.net
• dnschecker.org

Search for your CNAME records and confirm they’re resolving to SendGrid’s servers globally.

Step 9 — Verify Your Domain in SendGrid

Return to SendGrid > Settings > Sender Authentication. Find your domain and click “Verify”.

SendGrid will run a check against your DNS records. If everything is in order, you’ll see green checkmarks next to each record and a “Verified” status on your domain.

If verification fails, see the troubleshooting section below.

Setting Up Link Branding

Once your domain is authenticated, set up Link Branding as well. This customizes the URLs in your emails (click tracking, unsubscribe links) to use your own domain instead of SendGrid’s generic tracking domain.

Without link branding, your emails contain links like click.sendgrid.net/… — which looks suspicious to spam filters and hurts click-through rates.

To set up Link Branding:

1. Go to Settings > Sender Authentication
2. Click “Brand Your Links”
3. Enter the same domain you just authenticated
4. SendGrid will give you one more CNAME record — add it to your DNS the same way as before
5. Return and verify

Link-branded emails see up to 15% improvement in click rates, according to industry data from Litmus.

Troubleshooting Common Verification Issues

Even when you follow every step, verification can fail. Here’s what to check:

“CNAME record not found” Your DNS changes haven’t propagated yet, or the record was entered incorrectly. Double-check the Name and Value fields match exactly what SendGrid provided.

“CNAME record is incorrect” Often caused by your DNS provider appending the root domain automatically. Enter only the subdomain portion in the Name field, not the full hostname.

Cloudflare orange cloud (proxied) Turn off the Cloudflare proxy for these records. CNAME records for SendGrid must be DNS-only (grey cloud icon).

Using a wildcard CNAME Wildcards (*.yourcompany.com) can sometimes interfere with specific CNAME lookups. If you have one, consider adding the specific records separately.

Multiple MX/SPF conflicts If your root domain already has an SPF record, make sure it includes SendGrid’s sending infrastructure. Your subdomain should have its own clean SPF record.

How to Test Your SendGrid Custom Domain

Verification in SendGrid’s dashboard confirms DNS is set up correctly — but you should also send a real test email to confirm everything is working end-to-end.

Use these free testing tools:

• Mail-Tester.com — gives your email a deliverability score out of 10 and shows exactly which authentication checks pass or fail
• MXToolbox Email Health Report — checks SPF, DKIM, DMARC, and blacklist status for your domain
• GlockApps — tests inbox placement across Gmail, Outlook, Yahoo, and others

A fully authenticated domain on a clean IP should score 9.5–10/10 on Mail-Tester with all authentication headers passing.

What you’re looking for in headers:

• dkim=pass — confirms DKIM is working
• spf=pass — confirms your sending IP is authorized
• dmarc=pass — confirms DMARC policy is being applied

If all three show pass, your custom domain setup is working correctly.

What Happens to Your Deliverability After Setup

The improvements aren’t subtle. Here’s what properly authenticated senders typically see:

• Inbox placement improves by 15–30 percentage points for cold outreach campaigns
• Bounce rates drop by 20–40% as your domain builds a sending reputation
• Spam complaints fall significantly because ISPs trust authenticated senders more
• Open rates increase 10–20% simply because emails are reaching the primary inbox instead of promotions or spam
• Gmail’s new Google Postmaster Tools will start tracking your domain reputation — authenticated senders build positive domain reputation scores over time

According to Validity’s 2023 Email Deliverability Benchmark Report, senders with strong domain authentication see 96.5% inbox placement rates on average — compared to 55.6% for unauthenticated senders.

That gap is the difference between a working outbound machine and a broken one.

Conclusion

Adding a custom domain in SendGrid is one of the highest-leverage technical tasks you can do for your outbound program. It takes less than an hour to set up, but the deliverability improvements — better inbox placement, lower bounce rates, stronger sender reputation — compound over every campaign you run from that point forward.

The steps are straightforward:

1. Go to Settings > Sender Authentication in SendGrid
2. Start Domain Authentication and enter your subdomain
3. Copy the three CNAME records and add them to your DNS provider
4. Wait for propagation, then verify in SendGrid
5. Set up Link Branding with the same domain
6. Test with Mail-Tester to confirm everything is passing

That’s it. Your infrastructure is clean. Now the question is what you do with it.

Most teams set up perfect technical infrastructure and then watch their campaigns underperform — because deliverability is only one piece of the puzzle. Targeting, messaging, follow-up sequencing, and scaling systems are what actually turn inbox placement into booked meetings.

If you want to see what a complete, systemized outbound operation looks like, book a strategy meeting with SalesSo and we’ll walk you through it.