There are several reasons your message to your cohort may not have been delivered:
Email Addresses Must Match
The cohort lists are private, which means only people on the list can send email to it. In order to email the list, your return address on your email must match the location to which your Wharton email is forwarding. If it doesn’t, the message bounces to the list owner. So, for instance, if you were attempting to send an email to your cohort mailing list from your Wharton account, but you have your Wharton email forwarded to Gmail, it won’t go through.
Sample Error Message:
Is being held until the list moderator can review it for approval.
The reason it is being held:
Post by non-member to a members-only list
Either the message will get posted to the list, or you will receive
notification of the moderator's decision.
Note: Address forwarding information is updated nightly, so it may take up to a day for a forwarding change to reach the cohort list.
Attachment or Message Size
Did you have a file(s) attached to the message or any graphics in it? If so, another reason it might not have gone through is that the message's size is larger than the list's limits.