# Use the web inbox > Read, search, organize, compose, and reply from Startup Mail’s focused mail surface. ## Switch mailboxes Use the mailbox selector in the left navigation to move between addresses you can access. Shared and private mailboxes are marked separately. Unread counts belong to each mailbox. ## Work with conversations Messages are grouped into threads. Opening a thread marks it read and shows the complete conversation in chronological order. The inbox supports Inbox, Starred, and Sent views; archive and trash actions remove a thread from the active inbox without changing another user’s mailbox permissions. Search looks across the accessible conversation list. Compose suggests people you contacted recently without requiring a separate contacts database. ## Compose and reply Choose **Compose**, select an available sending mailbox, enter up to ten recipients in each recipient field, add a subject, and write plain or formatted content. Replies keep the existing thread relationship. Attachments are uploaded before the message is queued. A single attachment can be up to 5 MB, a message can contain up to ten attachments, and the entire message must stay under the configured 10 MB boundary. ## Delivery status An outgoing message first appears as queued. Provider feedback can move it to sent, delivered, or failed. A failed status is about that message delivery; repeated hard bounces or complaints can also suppress a recipient or pause workspace sending. > **HTML is treated as untrusted** > > Incoming HTML is cleaned and shown in a restricted frame. Remote resources are blocked so merely > opening a message does not silently load tracking content.