Attachment with .exe or a macro Excel doesn't deliver
Exchange Online blocks a default list of risky extensions. Macro files often go to Defender quarantine.
Try this first
- 1Check blocked extensions in Microsoft 365 Defender
- 2Send the file in a password-protected zip, share the password separately
- 3Or put it in OneDrive/SharePoint and share a link
- 4For macros: don't email at all, share internally only
When to bring us in
Temporary exceptions are possible, but prefer changing the file format over weakening the policy.
See also
- Our emails land in spam for some recipientsAlmost always an SPF, DKIM, or DMARC setting that is wrong or missing, or a sender name that mimics a well-known brand.
- Someone reports receiving phishing emails "from us"Read: spoofing. Someone is abusing your sender name, not necessarily your actual mailbox.
- An email bounces (NDR): delivery failedThe NDR text usually states the exact reason. Reading it is step one.
None of the above fits?
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Or skip the DIY entirely
Our Managed IT clients do not look these things up. One point of contact, a fixed monthly price, resolved within working hours.