Office 365 Limitations on Folders/Mail Items

Hello All,

I am in the process of migrating various mailboxes from an older Exchange 2003 installation to Office 365.

The users in question however have 600+ folders in their inbox, and i was curious as to the limitations of Office 365 in regards to the number of mail items, folders and so on.

2003 had major issues with such aspects and i am wishing to make sure that the same problems are not repeated before beginning this migration.
Who is Participating?
Vasil Michev (MVP)Connect With a Mentor Commented:
You should be fine. There is a limit of the total number of messages (500k) and the message size (35MB), but the only limitation regarding folders is the name ("/" is not an acceptable character).

Just in case, here's the link for message and recipient limits in O365:
wshtyConnect With a Mentor Commented:
afaik there is no folder limit in itself but only a folder item limit - in exchange 2003 it was a limit of 5000 objects in critical folders.

at exchange 2010 the limit has gone up to 100.000 objects.

for more information about the limit see here:

so i suppose that it won't be any trouble - just make shure that the users archive their mails regularly.
RobKanjAuthor Commented:
Yu've been great experts
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