It most likely would depend on what your internet connection can cope with,
if it is a slow connection, i recommend to stay to smallish files but if connection is fast, big files should be fine but i really do not know if there is any limits.
searching the web gives this response:
"No, but it's a good idea to limit your attachments to documents or files smaller than 1,000 Kilobytes (1MB). Large attachments increase the size of your email messages and make it more likely that the message will be rejected or mangled during its voyage to your recipient."
How to Increase Outlook PST File Size
File could be very big in size. Check your email's maximum allowable file size for attachments.
The maximum size of a PST file depends on the version of Microsoft Outlook. Outlook 2003 and 2007 have a user-defined maximum that defaults to 20GB and can't really get much bigger in practice as otherwise Outlook gets too slow and has problems. Older version of Outlook (such as Outlook 2000, XP, and 98) have a fixed limit of 2GB. If your .pst file gets bigger than 2GB then Outlook will report that it is corrupted. [Note: utilities like Stellar Outlook PST Repair can help split large .pst files and fix any corruption problems they might have.]
The minimum recognize Outlook PST File size when you create a new Outlook Data file will be 265 Kb.
Size of 1 pst in outlook is 2 gb
what is the maximum size of a file im ms publisher 2007
There is no maximum file size for a Roblox place. It depends on how large of a computer you have and how fast it is. the larger the computer, the bigger the file.
Microsoft Outlook creates a PST file, while you configure an account in Outlook. The PST stores copies of messages, calendar, notes, tasks, contacts and other items. PST file may get corrupted because of many reasons, in that case, you would be unable to open Outlook. The reasons could be Virus, improper outlook shutdowns, corruption in header files, pst file has reached maximum size limit etc. In that case you can use outlook utility, named Inbox repair tool to fix your pst file.
From TechNet: Set the Same Initial and Maximum Size Setting the paging file's initial size and maximum size to the same value increases efficiency because the operating system does not need to expand the file during processing. Setting different values for initial and maximum size can contribute to disk fragmentation.
Windows 7 has a maximum file size of 16 TiB.
The maximum data download for an email varies depending on the way the email is sent. If it is sent by SMTP the maximum size is 25MB and if it is sent by Outlook Web Access the maximum size is 10MB.
No, compacting Outlook emails does not harm them. Compacting emails simply reduces the size of the Outlook data file, which can help improve performance and free up disk space. Compacting emails does not delete any emails, but it does remove any deleted items from the data file.