Email with an attachment will not send

File size, connectivity or a provider restriction may be responsible.

Stop if unsure or if a new warning appears. Save your work before changes and ask IT before changing a work device. Never disclose passwords or recovery keys.

Save the draft and read the exact error. Check whether a short test message without sensitive information or attachments sends successfully.
Check the provider’s attachment-size limit. Several photos or videos may be too large together.
Reduce copies of the files or use a trusted sharing service with restricted access. Keep the originals and do not share confidential files publicly.
If a file type is blocked for security reasons, do not bypass the restriction by renaming it. Ask the recipient for an appropriate secure transfer method.

Test after each step and stop when the issue is solved. Checkmarks are not permanently saved.