Email Delivery Best Practices

Discover essential tips for crafting compelling email subject lines and engaging content to boost open rates and enhance communication.

Written by Juan Tobon (Collaborator)

Updated

Overview

Biller Genie automatically generates email subject lines and message content that follow industry best practices for reliable delivery across major email providers.

While these fields are editable, changing subject lines or message content incorrectly can increase the likelihood that emails are routed to junk or spam folders by services such as Google Workspace, Microsoft 365, and other corporate email platforms.

 

Warning!

Changing subject lines or message content in ways that resemble marketing, promotional, or automated bulk emails can negatively impact email delivery.

Email providers analyze subject lines and body content to determine whether a message should be delivered to the inbox, junk folder, or blocked entirely.

 

 

How Biller Genie Email Templates Work

Biller Genie includes multiple automated email templates that are triggered based on invoice activity and timing. These templates can be found in the Biller Genie portal under

  • Add-Ons > Invoice Messenger
  • Add-Ons > Reminders

 

Each template includes editable fields such as the header, subject line, and message body.

 

Available Email Templates

The most commonly used templates include:

 

Template Trigger
New Invoice Automatically sent when a new invoice is created
Paid Invoice Automatically sent once an invoice is marked as paid
Invoice Manually sent from Biller Genie account
Invoice Reminders Automatically sent based on reminder schedules and rules (configured under Add-Ons > Reminders)

 

New Invoice, Paid Invoice, and Invoice Reminders are system-triggered based on invoice activity. The Invoice template is merchant-initiated and sent manually.

 

Subject Line Best Practices

Biller Genie prepopulates subject lines using proven patterns that email providers recognize as transactional and legitimate. When modifying subject lines, follow the guidelines below.

Recommended Practices

  • Keep subject lines short, clear, and invoice-focused
  • Include invoice identifiers such as invoice numbers
  • Reference your business name using merge fields
  • Use neutral, transactional language

 

Examples:

  • Invoice #{InvoiceNumber} from {DBAName}
  • New Invoice: #{InvoiceNumber}
  • Paid: Invoice #{InvoiceNumber}

 

What to Avoid in Subject Lines

Avoid subject lines that resemble marketing or promotional emails, including:

  • Excessive punctuation (!!!, ???)
  • ALL CAPS wording
  • Emojis or symbols
  • Urgent or sales-driven language

 

Examples to avoid:

  • PAY NOW!!!
  • FINAL NOTICE – ACT FAST
  • LIMITED TIME OFFER
  • You must open this email immediately

These patterns are commonly flagged by spam filters and can reduce deliverability.

 

Message Body Best Practices

Email providers also analyze message content when determining whether an email is delivered to the inbox or routed to junk folders.

  • Keep messages professional and invoice-focused
  • Use clear spacing and readable formatting
  • Avoid excessive links or external URLs
  • Use standard punctuation and capitalization
  • Limit repeated keywords related to payment urgency

 

What to Avoid in Message Content

Avoid adding content that may be interpreted as promotional or automated bulk messaging, including:

  • Marketing or upsell language
  • Large blocks of bold or colored text
  • Excessive urgency or threatening language
  • Repeated calls to action beyond the payment link

 

Biller Genie's default subject lines and message content are designed to:

  • Align with transactional email best practices
  • Pass common spam-filter and reputation checks
  • Deliver consistently across major email providers
  • Reduce false positives in junk and spam filtering systems

While customization is supported, we strongly recommend keeping changes minimal and aligned with the original structure.

 

Confirming Successful Email Delivery

After making changes to subject lines or message content:

  1. Send a test invoice to yourself.
  2. Verify delivery to your inbox (not junk or spam).
  3. Confirm that customers receive invoices promptly.
  4. Verify that reminder and paid invoice emails are delivered as expected.

If emails are routed to junk folders after changes, revert to the original subject line or message structure.