Custom email senders
Use your own email address as the sender for all event communications instead of the default IO sender. This provides brand consistency and helps with email deliverability. For best deliverability, we recommend setting up both a custom web domain and a custom email address.
Why use custom email senders?
Brand recognition - Attendees receive emails from e.g. noreply@yourcompany.com instead of our default address.
Trust - Emails from your domain are more recognizable and trusted by your attendees.
Deliverability - Properly configured custom senders improve email delivery rates.
Delivery methods
When setting up a custom domain, you choose how email is delivered:
IO email (via AWS) - Uses IO's included email delivery infrastructure (Amazon SES). This is the default and recommended option. You'll add DKIM and SPF DNS records to prove domain ownership and authorise sending.
Custom SMTP server - Routes email through your own or a third-party SMTP server. You'll provide the host, port, credentials, and TLS settings. Use this if your organisation requires email to flow through a specific server.
Setting up custom email senders
- Navigate to Account Settings > Custom domains to create a new domain
- Enter the email address you want to use as sender
- Choose a delivery method
- Add the required DNS records
- Once verified, your custom sender is active
DNS configuration
For IO email (via AWS), you'll add:
SPF record - Authorizes IO to send email on behalf of your domain.
DKIM records - Authenticate emails to improve deliverability.
DMARC record (optional) - Additional authentication for maximum deliverability.
For Custom SMTP, DNS requirements depend on your SMTP provider.
Exact record values are provided in IO when setting up your custom sender.
Testing
After setup, send test emails to verify:
- Emails appear from your custom sender
- Authentication passes (check email headers)
Deliverability testing
We’ve had good success using Mailreach to test the deliverability of invitations before sending.