What you’re seeing
- A bounce such as 552 5.3.4 saying the message size exceeds the maximum allowed.
- Smaller emails send fine, but anything with a large PDF, drawing or scan fails.
- The office scanner fails to email multi-page scans.
- Raising the limit in one setting made no difference.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- Exchange enforces size limits at several layers, including the organization, individual connectors and each mailbox, and the lowest one wins.
- Outlook on the web, mobile sync and other web services have their own request size limits that are separate from mail transport.
- Attachments grow by roughly a third when encoded for email, so a file under the limit on disk can exceed it once sent.
- A spam filter, mail gateway or cloud filtering service in front of Exchange applies its own lower cap.
- The recipient's mail system has a smaller limit than yours, so the bounce comes from their side.
Why it matters
Architects, engineers, legal firms, healthcare offices and anyone handling scanned paperwork depend on sending large files. When attachments bounce, staff switch to personal file-sharing sites or USB drives, which puts client data outside your control and can breach confidentiality obligations. Projects slow down while people split files or find workarounds, and clients who cannot send you documents get frustrated. Limits that differ across systems also create unpredictable behavior that wastes help-desk time.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Is there a sensible maximum attachment size?
It depends on how you work and who you exchange mail with. Very high limits can strain the server and still fail at the recipient's end, so we recommend a balanced figure and explain the trade-off in plain English.
Should we be emailing large files at all?
Sometimes a secure sharing link is the better option for very large files. Our engineer can explain where the limits sit today and which approach suits the files your team sends most.