Bulk Update Mailbox Signatures

PATCH https://app.mailivery.io/api/v1/bulk-action/updateSignature

Create or update signatures for multiple mailboxes in a single request.

Use this endpoint for:

• Initial signature setup for many new mailboxes.
• Company-wide rebrands or address changes.
• Synchronizing signature data from external systems (CRM, HRIS).

Each mailbox can have different signature details in the same batch.