# Developers

- [AcyMailing 5 Developer Documentation](/old/developers/acymailing-5-developer-documentation.md)
- [Customize the way the content inserted in emails by plugins](/old/developers/customize-the-way-the-content-inserted-in-emails-by-plugins.md)
- [Conditional display](/old/developers/conditional-display.md)
- [Multiple queue system](/old/developers/multiple-queue-system.md)
- [External subscription form](/old/developers/external-subscription-form.md)
- [Subscription via URL](/old/developers/subscription-via-url.md)
- [Fabrik Form and AcyMailing](/old/developers/subscription-via-url/fabrik-form-and-acymailing.md)
- [ChronoForm and AcyMailing](/old/developers/subscription-via-url/chronoform-and-acymailing.md)
- [RSForm!Pro and AcyMailing](/old/developers/subscription-via-url/rsform-pro-and-acymailing.md)
- [BreezingForms and AcyMailing](/old/developers/subscription-via-url/breezingforms-and-acymailing.md)