[18.0][ADD] fetchmail_s3: receive email from S3-compatible buckets

[dnplkndll]

Summary

Add a new "S3 Bucket" server type to Odoo's incoming mail servers. Polls an S3 bucket for raw email files (.eml) and processes them through mail.thread.message_process.

Use case

AWS SES inbound email rules store messages in S3. This module picks them up on the fetchmail cron schedule, processes them into Odoo records (leads, tickets, DMS documents, etc.), then archives or deletes the S3 objects.

Works with any S3-compatible storage: AWS S3, MinIO, Hetzner Object Storage, DigitalOcean Spaces.

Why not IMAP?

Approach	Cost	Maintenance
SES + S3 + this module	~$0/month	Zero — serverless
Google Workspace IMAP	$7/user/month	OAuth refresh, IMAP polling
Microsoft 365	$6/user/month	Per-mailbox licensing

For cloud-native deployments, S3 is the natural choice. SES is free for the first 1,000 emails/month.

Design

Follows the same extension pattern as google_gmail and microsoft_outlook:

• Adds server_type = 's3' via selection_add
• Overrides connect(), button_confirm_login(), fetch_mail()
• Uses boto3 for S3 operations (paginated listing, get, copy, delete)
• Processed emails are archived to a configurable prefix or deleted

Configuration

1. Set up SES inbound email → S3 bucket
2. Create incoming mail server in Odoo with type "S3 Bucket"
3. Configure bucket, prefix, region, IAM credentials
4. Click "Test & Confirm"
5. Fetchmail cron handles the rest

Dependencies

• boto3 (Python package)

🤖 Generated with Claude Code

[dnplkndll]

CI test failures are caused by oca_list_external_dependencies not finding fetchmail in the addons path, despite it being a core Odoo CE module. The fetchmail module is in odoo/addons/fetchmail/ and should be available.

The same error pattern exists for test_auditlog (setup/test_auditlog fails with 'Unsupported odoo version 18.0') — this is a pre-existing repo issue.

Pre-commit passes cleanly. The module installs and tests correctly against Odoo 18 CE in our own CI.