CIT's Exchange system limits the size of email messages, including their attachments, to 25 MB. The size limit is required with Office 365.

Messages that exceed the size limits are rejected by Exchange. Note that email rejections can also occur as a result of CIT's efforts to block spam.

Cornell staff considering sending attachments (large or otherwise) have options, including:

What's the biggest attachment I can send?

http://www.cit.cornell.edu/computer/email/emailfaq.html#attachsize
Limited information specific to the limits related to CIT's e-list service

http://www.cit.cornell.edu/computer/elist/lyris/post.html[ http://it.chem.cornell.edu]