SMTP email relay setup.
Connect your own SMTP relay so you control the sending address for every transactional email Bidsquare sends — invoices, outbid notices, registration approvals and more. This guide covers what you need, how to size it, and what to send us to connect it.
What is a transactional email?
The system-generated messages your buyers and consignors actually rely on.
It's now possible to connect your own SMTP relay for transactional emailing within our White-Label and Vault systems. SMTP ("simple mail transfer protocol") lets you control the specific sending address for all transactional emails triggered from the admin.
Transactional emails are messages sent in response to an action a user takes on your site. They contain content specific to that user and are typically sent to individuals one at a time.
Password-reset emails, outbid notices, registration approvals, account creation, invoices — every automatic, system-generated message that may be sent to a user.
SMTP controls the address your emails are sent from. To edit the wording, subject line, and branding of each template, see the Editing Email Templates guide.
Recommended providers
Use a service built for mass transactional sending — not a personal mailbox.
If you don't already subscribe to this kind of service, these are our recommended providers:
| Provider | Where to start |
|---|---|
| SendGrid | sendgrid.com — Email API / SMTP service |
| Mailchimp Transactional | mailchimp.com — Transactional email A Mailchimp "Standard" marketing plan is required to access these features. |
| Brevo formerly Sendinblue | brevo.com — Transactional email |
The transactional service provided by Bidsquare Vault covers every automatic or system-generated email (password resets, invoices, account creation, registrations, approvals, bid notices and more). It's highly recommended that a dedicated mass-emailing service such as Mailchimp Transactional or SendGrid is used to send them.
Sizing your subscription
There's no exact science — but this rule of thumb gives you safe headroom.
Take the total number of users active in your sales (buyers and consignors), multiply by the number of email types that go out each auction for both user types (in the most extreme scenario, roughly 15–20 emails per person per auction), then multiply that by the number of auctions you run per month.
5,000 users + 2,000 consignors = 7,000 total. If ~10% are active in every sale, that's 700 active people. 700 × 15 emails = 10,500. Across 2 single-day auctions per month: 10,500 × 2 = 21,000 emails per month.
Apply your own numbers to this equation and the rough figure should give you enough headroom to avoid hitting limits. Most providers auto-scale to supplement usage if you go over, but it's best to avoid that scenario — hitting a sending limit can affect deliverability of important emails (such as customer invoices) if restrictions are imposed.
Important information
Choosing the wrong kind of service can get your domain blacklisted.
Using services such as Office 365, Gmail, Constant Contact, or any other service not correctly built for mass-emailing or suitable as an SMTP relay may breach those services' sending limits. That can drive up spam reports and lead to the blacklisting of a connected domain. It's incumbent on users to select an appropriate service; Bidsquare cannot be held responsible for issues arising from an improper or unsuitable third-party emailing platform.
Any SMTP service must be connected and verified with your Bidsquare (white-label) domain — with the appropriate DNS / DKIM / SPF records updated — before SMTP can be used successfully.
Enter your SMTP credentials
Once your service is in place and your domain is verified, add your credentials directly in the admin — no need to contact support.
Go to Settings › Auction Settings › Email Settings and enter the following details to connect your SMTP relay:
| Detail | Example |
|---|---|
| SMTP host | smtp.mandrillapp.com (Mailchimp Transactional) or smtp.sendgrid.net (SendGrid) |
| SMTP port | 587 (default) |
| SMTP security | TLS (default) |
| SMTP username | Typically the login email for the main account holder of the chosen service |
| SMTP password | Or the API key, if using an API service |
| FROM email address | no-reply@auctionhouse.com |
| FROM name | Your auction house name |
The setup is fully self-serve — enter your credentials directly in the admin. If you run into any issues, email support@bidsquare.com or call 1-800-657-0092 and we'll help you through it.
Using Mailchimp Transactional as your SMTP provider
How it relates to the Mailchimp Marketing API — and what you need before you can use it.
Mailchimp offers two distinct email services that are sometimes confused. If you plan to use Mailchimp for both marketing and transactional email, it's worth understanding how they relate before you set either up.
| Service | What it does | What you need |
|---|---|---|
| Mailchimp Marketing API | Syncs bidder opt-ins to your Mailchimp audience for marketing campaigns. Covered in the Mailchimp Marketing Sync guide. | Any active Mailchimp plan |
| Mailchimp Transactional (formerly Mandrill) | Routes your Bidsquare system emails (invoices, approvals, outbid notices) through Mailchimp's sending infrastructure so they arrive from your own domain. | Mailchimp Standard plan as a prerequisite, plus the Transactional add-on |
The Mailchimp Standard marketing plan is a prerequisite for the Transactional add-on. If you intend to use both services, it's more cost-effective to sign up for the Standard plan first and add Transactional at the same time — rather than starting with a lower plan and upgrading later.
Common problems
The issues that come up most during setup and after go-live.