How to Send Invoice Emails with Kotlin
Learn how to send invoice emails from your Kotlin application using AISend's AI-powered email API. This guide covers setup, implementation, and best practices for sending billing invoices to customers.
What are invoice emails?
Invoice emails are transactional emails triggered by user actions, specifically for sending billing invoices to customers. These emails are critical to your application's user experience — if a invoice email doesn't arrive, users lose trust in your product. Invoice emails typically have high open rates (60-80%) because recipients are expecting them. This makes deliverability especially important — you need an email API that ensures these messages reach the inbox, not the spam folder. AISend's AI-powered routing selects the best email provider for each recipient, maximizing inbox placement for your invoice emails.
Setting up AISend with Kotlin
Start by creating a free AISend account at aisend.app — no credit card required. From your dashboard, create an API key. Call AISend's REST API from Kotlin using your preferred HTTP client. The API accepts JSON payloads with from, to, subject, and html fields. For production use, store your API key in environment variables — never hard-code credentials in your source code.
Sending invoice emails
To send a invoice email, make a POST request to the AISend API with four fields: from (your verified sending domain), to (the recipient's email), subject (a clear, descriptive subject line for your invoice email), and html (the email body). For invoice emails specifically, keep the content focused and actionable — include only the information the user needs for sending billing invoices to customers. Avoid promotional content in transactional emails as it can hurt deliverability and may violate anti-spam regulations. AISend's AI automatically scores your content for deliverability before sending.
Best practices for invoice emails in Kotlin
Send invoice emails immediately when triggered — delays frustrate users, especially for time-sensitive emails like invoice. Use a background job queue to avoid blocking your application's response time. Include clear branding so users recognize your email. Keep subject lines descriptive and specific (e.g., "Your invoice from [AppName]"). Set up webhook handlers to track delivery status and handle bounces. Always include both HTML and plain text versions for accessibility. Use AISend's domain verification to set up SPF, DKIM, and DMARC for maximum deliverability.
Why use AISend for invoice emails?
AISend is built specifically for transactional emails like invoice notifications. AI-powered multi-provider routing ensures your emails reach the inbox by selecting the best provider (AWS SES, Postmark, or SMTP) for each recipient. Content scoring catches deliverability issues before they affect your sender reputation. And the API is designed to be developer-friendly — send your first email in under 5 minutes with the free tier (1,000 emails/month, no credit card required).