271 feature support role based email validation in socketmap user exist check

[Aravinda-HWK]

📌 Description

Now, the socketmap service will check role-based emails in the user-exists check. When LMTP transfers the email to the raven, it checks whether that mail is role-based mail or user-defined mail, based on that it saved in relavant database with the correct prefix. ex: user_ or role_

• Closes [FEATURE] Support role-based email validation in socketmap user-exist check #271

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🔍 Changes Made

• user-exists in sockermap accept role-based email addresses
• LMTP service checks whether the email address is role-based or user-based email, always hitting the cache.

✅ Checklist (Email System)

• Core IMAP commands tested (LOGIN, CAPABILITY, LIST, SELECT, FETCH, LOGOUT).
• Authentication is tested.
• Docker build & run validated.
• Configuration loading verified for default and custom paths.
• Persistent storage with Docker volume verified.
• Error handling and logging verified
• Documentation updated (README, config samples).

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🧪 Testing Instructions

To test the server, use the instructions in the README in the test directory.

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📷 Screenshots / Logs (if applicable)

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⚠️ Notes for Reviewers

Need to create a role in the thunder ui and send an email to that role's email address.

[gemini-code-assist]

Code Review

This pull request introduces socketmap-based identity resolution for LMTP delivery, allowing envelope recipients to be mapped to specific mailbox identities, such as role-based mailboxes. The changes include a new socketmap client, role validation logic against the Thunder IDP, and updates to the database manager to handle explicit mailbox paths. Feedback focuses on several performance and logic issues: the delivery process lacks deduplication when multiple recipients map to the same identity, leading to duplicate emails; the socketmap client inefficiently opens a new connection for every recipient; negative lookup results are not cached, which could lead to performance degradation; and the role validation logic fetches all roles for local filtering instead of using server-side queries.

[maneeshaxyz]

LGTM.