Technical and operational analysis of attachment bottlenecks and secure link workflows.
Send attachments with your Gmail message - Computer - Gmail Help Skip to main content Gmail Help Sign in Google Help Help Center Community Gmail Privacy Policy Terms of Service Submit feedback Send feedback on... This help content & information General Help Center experience Next Help Center Community Gmail Send attachments & images Send attachments with your Gmail message Send attachments with your Gmail message Add attachments, like files or photos, to your emails. Learn how attachments work in Gmail There are limits to the size of attachments for Gmail: For personal Gmail accounts, the limit is 25 MB.
For work and school accounts, your Google Workspace administrator sets the attachment sending limits and attachment receiving limits . If your total attachment size is greater than the limit, Gmail automatically removes the attachment and adds it as a Google Drive link in the email. Send attachments with confidential mode Tip : If you're using Gmail with a work or school account, contact your admin to make sure you can use confidential mode.
Tip : If you've already turned on confidential mode for an email, go to the bottom of the email, then click Edit . If you choose "No SMS passcode," recipients using the Gmail app will be able to open it directly. Fix issues with attachments in Gmail Attachments might be unavailable Your network administrator or Internet provider probably blocked "mail-attachment.googleusercontent.com," the domain Google uses to host attachments.
Blocked for security reasons To prevent viruses, Gmail doesn't let you attach executable files , like files ending in .exe. Learn how to resolve the ”Gmail’s adding files” error message If you upload files from another device, wait until the upload completes. Related resources Send Google Drive attachments in Gmail Files types blocked in Gmail Computer Android iPhone & iPad More Need more help?
Restrictions and limitations in OneDrive and SharePoint - Microsoft Support Skip to main content Microsoft Support Support Support Home Microsoft 365 Office Products Microsoft 365 Outlook Microsoft Teams OneDrive Microsoft Copilot OneNote Windows more ... If a file or folder you're trying to upload to OneDrive contains any of the characters listed below, it may prevent files and folders from syncing. Characters that aren't allowed in file and folder names in OneDrive for home or OneDrive for work or school " * : < > ?
For Office desktop win32 apps: If you're saving an Office file via the Backstage view to a OneDrive or SharePoint folder, you won't be able to save the file if the folder name contains ; (semicolon). Invalid file or folder names Applies to: These names aren't allowed for files or folders: .lock , CON , PRN , AUX , NUL , COM0 - COM9 , LPT0 - LPT9 , _vti_ , desktop.ini , any filename starting with ~$ . Invalid or blocked file types Applies to: Temporary TMP files will not be synced to OneDrive.
Outlook .PST files are supported, however they are synced less frequently compared to other file types to reduce network traffic. To prevent uploading .PST files from the OneDrive sync app, read Blocking syncing of specific file types . To move .PST files out of OneDrive, read How to remove an Outlook PST data file from OneDrive .
Outlook may show errors after .PST files are migrated because it is still looking for .PST files at original location. If you are a OneDrive for work or school user, some file types may be blocked on your organization's SharePoint site. For security reasons, a number of file names and extensions can't be uploaded since they are executable, used by SharePoint Server, or used by Windows itself.
This model prioritizes controlled delivery, recipient scope, and revocation behavior instead of persistent account-centric storage access.
Attachment pipelines typically impose size constraints, limited visibility, and weak revocation controls once messages are forwarded.
Expiration should match transfer sensitivity and business context, with shorter windows for externally shared regulated data.
Teams should confirm sender identity, recipient scope, file classification, and integrity checkpoints prior to release.
Capture transfer metadata, policy decisions, recipient validation steps, and closure timestamps in auditable records.
They remove mailbox size constraints, centralize controls, and allow expiration or revocation after successful handoff.
Security model · HIPAA readiness · Verify encryption · Whitepaper