Connect SendGrid
Established and scalable. The username is literally "apikey" — read Step 2.
Twilio SendGrid is a well-known, scalable provider. The one quirk that trips everyone up: your SMTP username is the literal word apikey — not your email.
SMTP settings at a glance
| Setting | Value |
|---|---|
| Server | smtp.sendgrid.net |
| Ports | 587 (STARTTLS, recommended) · 2525 · 25 · 465 (SSL) |
| Username | apikey (type exactly this, for every account) |
| Password | Your SendGrid API Key (from Step 2) |
Note: SendGrid no longer has a permanent free tier — new accounts get a 60-day trial (100 emails/day), then need a paid plan.
Step 1 — Authenticate your domain
- In SendGrid: Settings → Sender Authentication → Authenticate Your Domain.
- Pick your DNS provider, enter your domain, and add the CNAME records SendGrid generates.
- Click Verify. (Quick alternative for testing: Single Sender Verification verifies one From address.)
Step 2 — Create an API Key (this is your password)
- Settings → API Keys → Create API Key.
- Name it, choose Restricted Access and enable Mail Send (or Full Access).
- Click Create & View and copy the key now — it's shown only once (starts with
SG.).
Step 3 — Paste into Mailbo
- Settings → SMTP & sending → click the SendGrid tile.
- Sender: From email (on your authenticated domain) + From name.
- Credentials: Username =
apikey· Password = your API Key. - Save, then Send test email.
Troubleshooting
| Problem | Fix |
|---|---|
| Auth fails | Username must be the literal apikey, and password must be the API Key (not your account password). |
| "Sender Identity" error | Finish Domain Authentication (or Single Sender Verification) in Step 1. |
| Key doesn't work | The key needs the Mail Send scope; and watch for stray spaces when pasting. |
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Last updated 6/15/2026← More in Sending & Deliverability