Provider guide · Scaleway
Transactional Email is the SES of the European cloud: a plain SMTP relay run from Paris, billed by the thousand. Nothing about it is hard, but two things surprise: the credentials come from IAM, with a Project ID as the username and the secret key of an API key as the password, and no email leaves before your domain is validated.
1 · Credentials
Everything happens in the Scaleway console, in two visits: one to Transactional Email for the domain, one to IAM for the key pair.
Under Domains & Web Hosting, then Transactional Email, set the four DNS records Scaleway hands you: SPF, DKIM, DMARC and MX. All four are required before anything sends, and validation can take up to 48 hours.
Give it a policy granting the Transactional Email permissions on your Project. An application rather than your own user is Scaleway’s recommended shape.
Copy the secret key immediately; it is shown once.
On the dashboard of the Project holding the domain. That UUID, not an email address, is your SMTP username.
The pair is unusual twice over, so it bears repeating: the username is the Project ID, and the password is the secret key of the API key, not its access key. An IAM application rather than your own user is Scaleway’s recommended shape, and it keeps the key alive when people move on.
2 · In the plugin
Selecting the Scaleway preset fills the server (smtp.tem.scaleway.com), the port (587) and the encryption (TLS). What remains came from the console.
The Project ID of the Project where the domain was added.
The secret key of your API key.
Any address on the validated domain. The local part is yours to invent; the domain is not negotiable.
Save, then use Send Test Email. If authentication fails, look at what landed in the password field: the access key is the classic slip, and only the secret key authenticates.
3 · Pitfalls
Scaleway’s hurdles are administrative rather than technical: an identity check on the domain, another on the key, and a quota that counts differently than you expect.
Every other provider wants an email address or a generated login; Scaleway wants the UUID of the Project in which the Transactional Email domain was created, with the secret key of an API key as the password. The access key and the secret key look alike, and only the secret one authenticates. It is displayed once, at creation: lost, there is nothing to recover, and the path is generating a new API key.
For a domain hosted elsewhere, the four DNS records, SPF, DKIM, DMARC and MX, are mandatory and checked before Scaleway lets anything out; validation can take up to 48 hours. The checks then keep running for the life of the domain, so a record cleaned up during a DNS migration quietly invalidates sending. Two details from the fine print: the recursive SPF include directive is not supported, and a domain registered at Scaleway can have all records set automatically.
One message to one recipient with three others in CC is four emails, against both the bill and the quota. The default ceiling is 10,000 emails per month, raisable on request, and the free allowance of the Essential plan is 300 emails per month per organization, then about €0.25 per thousand as of July 2026. The plugin’s own volume alerts make a decent early warning on the way to either ceiling.
Transactional Email runs only in the fr-par region. In the plugin there is nothing to choose, the relay hostname carries no region, but the domain, the key and the console resources all live there, and your email is processed in France. For many sites that pick Scaleway, that residency is the point.
The email log keeps the exact error message the server returned, which is the fastest route to the cause. The documentation walks through the common ones.
There is a guide like this one for each of the twelve presets, from Gmail to Amazon SES, and the plugin takes any other SMTP server too.