Open the full message
A message list is designed to help you scan many messages quickly. Its rows include a count of attachments, but not the message body or the full attachment records. Select or read the individual message to retrieve its text, HTML, and attachment details such as name, size, type, and whether a file is inline in the message.
Attachment links are returned with the full message and are time-limited signed URLs. Use the link from the current message response to download or display the file, rather than saving it for later or reconstructing a URL. If you need the file later, download it to an approved storage location while the link is valid and handle it under your normal data rules.
When an attachment cannot be opened
A full message can describe an attachment while its URL is null. This can happen when the attachment bytes could not be stored, including when mailbox or storage quota is full. In that case, the metadata helps identify the missing file, but it does not provide a working download location.
Check the mailbox's available usage and whether the message reports an attachment link. If the bytes were not retained, ask the sender to resend the file after the storage issue is resolved. Do not assume that marking the message read, refreshing the list, or copying the attachment name will restore missing bytes; share only the message ID and sanitized details when requesting help.