Why This Matters
Before your mailbox moves from HCL Notes to Exchange Online, there is one quick bit of housekeeping worth doing: finding and clearing out emails that carry very large attachments.
Exchange Online has a maximum size of about 149 MB for a single email. Any message bigger than that can fail to transfer during the migration - and you do not want an important email left behind. A few minutes of cleanup now means a smoother move.
The good news: this only affects a handful of emails. Almost everything in your mailbox is a few kilobytes (KB) and nowhere near the limit. You are only hunting for the rare giants.
Understanding Email Sizes
When you sort your mail by size, Notes shows a number next to each message:
- 8K means 8 kilobytes - tiny, a normal email
- 26K or 43K - still small, no action needed
- 11.9M means 11.9 megabytes - a large email, but under the limit
- 40.7M means 40.7 megabytes - large, and worth a look
The number to watch for is anything approaching or above 149M (149 megabytes). Those are the only ones you need to act on. If the biggest email in your mailbox is well under 149M, you are already done - no action needed.
Find Your Largest Emails in Notes
The trick is to sort your entire mailbox by size, largest first. Here is how.
Step 1 - Turn off "Group by Date"
By default, Notes groups your inbox into Today, Yesterday, Last Week, and so on. That grouping gets in the way of sorting by size, so switch it off first.
- Click the Show menu at the top right of your mail
- Remove the check mark next to Group By Date
Your inbox will now appear as one continuous list instead of being split into date groups.
Step 2 - Open "All Documents" and sort by Size
- In the left sidebar, click All Documents - this view shows every email in your mailbox, not just your inbox
- Make sure the view is fully expanded so you can see the column headers across the top
- Find the Size column and click its header to sort by size
Don't see a Size column? Make sure you are in the All Documents view and the list is fully expanded - the Size column will appear across the top.
Step 3 - Scroll to the biggest emails
Click the Size column header again if needed so the list is sorted with the largest emails at the top. Scroll up or down until you can see your biggest messages and their sizes.
Now look at the numbers. Is anything at or near 149M? If not, you are finished. If yes, move on to the next section for those specific emails.
What to Do With a Large Attachment
For any email at or above the 149 MB limit, you have two choices.
If you want to keep the attachment: save it somewhere else first, then clear it from the email.
- Open the email and save the attachment to your network share (or Milo)
- Once it is safely saved, either delete the email or remove just the attachment
- The important file is preserved, and the oversized email is gone
If you no longer need it: simply delete the email. That removes the attachment along with it.
Either way, the goal is the same - no single email left over 149 MB when your mailbox moves.
Quick Reference
| Step | What you do |
|---|---|
| 1 | Turn off Group By Date in the Show menu |
| 2 | Open All Documents and click the Size column to sort |
| 3 | Sort largest first and look for emails near 149M |
| 4 | Keep it? Save to your share (or Milo), then delete the email |
| 5 | Don't need it? Just delete the email |
What If I Miss One?
Don't worry about being perfect. If a large email cannot be moved, it simply is not migrated, and IT can help you recover or handle it afterward. Doing this cleanup ahead of time just makes the move cleaner and keeps your new Outlook mailbox tidy from day one.
Need Help?
If you are unsure whether an email is too large, or you want a hand clearing one out:
- Check the FAQ on this site for quick answers about the size limit
- Ask a colleague who has already done their cleanup
- Contact the SLSMC IT Service Desk