Sending replies through a transactional email API

Instead of an SMTP password you can send replies through a sending API. Go to Settings -> Email channel and open the Transactional e-mail API section.

Supported providers:

• Postmark
• SendGrid
• Resend
• Brevo
• Mailgun
• Amazon SES
• Elastic Email
• Mailjet
• Mailchimp Transactional (Mandrill)

What you need:

1. An API key from the provider with permission to send mail. For Amazon SES paste the key as ACCESSKEYID:SECRETACCESSKEY:REGION, for Mailjet as APIKEY:APISECRET. The required format is shown as a placeholder in the API key field.
2. A sender address that is verified in that provider, otherwise sending is rejected.
3. Optionally IMAP details, so incoming mail is still fetched into tickets. A sending API only sends; receiving still happens over IMAP or your provider inbound route.

EspressoDesk stores the API key encrypted with AES-256-GCM and verifies it when you save. Threading headers (In-Reply-To, References) and the ticket reference in the subject are sent with every message, so customer replies stay in the same ticket.

Deliverability still depends on your domain: keep SPF, DKIM and DMARC configured for the sending domain at the provider you choose.