Support configurable Gravatar-compatible avatar backends

Feature requests
1

Support configurable Gravatar-compatible avatar backends (e.g., ad2image, custom URLs, initials fallback)

1) What is your original issue/pain point you want to solve?

Currently, Zammad only supports its built-in image service or manual uploads for user/organization avatars. Many organizations would like to use internal, privacy-preserving avatar sources that are compatible with the Gravatar API, such as ad2image, but Zammad does not provide a way to configure a generic Gravatar-compatible avatar endpoint.

2) Which are one or two concrete situations where this problem hurts the most?

  • Organizations with privacy requirements cannot use public Gravatar or the Zammad image service, but have their own AD/Exchange/LDAP-backed avatar services that provide Gravatar-compatible endpoints (e.g., ad2image).
  • Mixed environments where some users do not have avatars in external/global services but can be displayed via internal systems.

3) Why is it not solvable with the Zammad standard?

  • Zammad does not allow configuring a generic, arbitrary Gravatar-compatible URL for avatar lookups. The code currently expects a very specific API and hardcodes the base URL.
  • There is no setting to customize the API path or append the email hash to a custom URL.

4) What is your expectation/what do you want to achieve?

  • Add support for a configurable Gravatar-compatible avatar backend:
    • Admins can configure the whole URL path (prefix), with Zammad appending only the hash of the normalized mail address.
    • Allow configuration of default query parameters (such as fallback mode: d=initials).
    • Use initials as a visual fallback if no image is found (fallback can be via avatar service or rendered client-side/server-side by Zammad).
  • Document how to use the feature for open-source solutions like ad2image.

More Useful Information

  • Example of a compatible API: https://ad2image.example.com/gravatar/<sha256-hex-hash-of-lowercase-trimmed-mail-address>?d=initials&s=200
  • Gravatar API documentation: Avatars – Gravatar For Developers
  • This flexibility allows organizations to use a variety of internal, external, or cloud-hosted avatar providers now and in the future.

Anything else which you think is useful to understand your use case:

  • Enhances privacy and compliance for regulated organizations
  • Provides feature parity with other products that can leverage Gravatar-compatible internal avatar solutions