Send email with the Brevo API when your VPS blocks SMTP

Some VPS providers (DigitalOcean, Vultr, Linode and others) block the SMTP ports (465, 587) by default to fight spam, so sending mail over plain SMTP (Gmail SMTP, for example) from a VPS fails with a timeout or connection refused. This guide uses the Brevo HTTP API v3 instead - it talks over HTTPS on port 443, which is never blocked - to send verification emails, and also fixes the wrong sender address showing up in the inbox.

Throughout, example.com is your domain, [email protected] and [email protected] are sender addresses, MyApp is your application name, and <account-id> and <brevo-code> are codes Brevo generates for you. Replace them with your real values.

Quick reference

1. Sign up: create a free account on Brevo.
2. Verify the sender email: go to Senders, Domains & Dedicated IPs > Senders, add the sender email and click the confirmation link in your inbox.
3. Verify the domain (if you send from a custom domain): open the Domains tab, add the domain, then create 3 DNS records: TXT (DKIM), TXT (SPF) and CNAME (Return-Path).
4. Get the API key: Profile menu > SMTP & API > API keys & MCP tab, click Generate a new API key (it looks like xkeysib-...). Do NOT take the SMTP key.
5. Configure the app: put the new API key in .env, then restart Docker (docker compose down and docker compose up -d --build).

Step 1: Create a Brevo account

Brevo has a free-forever plan that allows 300 emails/day - plenty for OTP and account verification emails.

1. Open the home page brevo.com.
2. Click Sign up free in the top-right corner.
3. Sign up with Google for speed, or with a regular email address.
4. Fill in the personal/company details they ask for (no credit card required).

Step 2: Verify the sender

1. In the Brevo dashboard, open Senders, Domains & Dedicated IPs (in the menu at the bottom right, or in the top-right corner).
2. Select the Senders tab.
3. Click Add a sender.
4. Enter the details:
   • From Name: the display name of the sender, e.g. MyApp or MyApp Admin.
   • From Email: the address that will send the mail, e.g. [email protected] or [email protected].
5. Open your inbox, find the email from Brevo and click the Verify button/link.
6. Make sure the sender status in Brevo changes to Active/Verified.

Step 3: Verify the domain

If you send from a custom domain (e.g. [email protected]), recipients will often see a strange sender such as admin@<account-id>.brevosend.com instead of your actual address.

Why: the sender domain is not verified yet, so Brevo automatically routes the email through one of its own subdomains to keep it out of Spam.

How to fix it:

1. Go to Settings > Senders & Domains (or the equivalent dashboard section) and select the Domains tab.
2. Click Add a domain and enter your domain (e.g. example.com).
3. Add the 3 DNS records Brevo asks for (table below) in the DNS management page of your domain (Cloudflare, MatBao, Tenten...).
4. Once DNS is configured, go back to Brevo and click Verify. Allow a few minutes (up to a few hours) for DNS to propagate.
5. After verification succeeds, add the sender [email protected] again as in Step 2. Mail will now show the correct [email protected] and stay out of Spam.

The three DNS records to create:

The exact value of each record is shown on the Brevo domain page - copy it verbatim into your DNS management page.

Step 4: Get the API key

1. Click your Profile in the top-right corner of Brevo and choose SMTP & API.
2. This screen has 2 tabs: "SMTP" and "API keys & MCP".
3. Select the API keys & MCP tab.
4. Click Generate a new API key.
5. Give it a memorable name (e.g. website-prod-api).
6. Click Generate.
7. Copy the key (xkeysib-...) immediately. It is shown only once.

Step 5: Configure the application (.env)

With everything in hand, open the .env file on the VPS (or your local machine) and update the settings. The variable names below come from a sample app - rename them to match yours:

# 1. Send through the HTTP API (brevo) instead of traditional SMTP
Email__Provider=brevo

# 2. Paste the API key (starts with xkeysib-) from Step 4 here
Email__BrevoApiKey=xkeysib-<your-api-key>

# 3. Use EXACTLY the email you verified in Step 2
Email__SenderEmail=[email protected]

# 4. Sender display name (should match the From Name in Step 2)
Email__SenderName=MyApp

Restart the Docker application:

docker compose down
docker compose up -d --build

Troubleshooting