Question:
I know that I can spot mailboxes over a certain size using the Mailbox Storage Information report template, but it will not let me send a message to each concerned individual.

Answer:
You can easily achieve this through Mailbox Storage Information by selecting these options.

• Selection tab: Select All organization mailboxes;
• Filter tab: Define your size criteria, for example Total item size (MB) Is greater than 512;
• Content tab: Select the Mailbox storage (item size and count) option;
• Compose for tab: Select the Compose individual report for selected mailboxes option, Send to: Email address, and the file format of the attached report - for example, Portable Doc Format (PDF). You can create a custom message template if you wish to deliver a specific information to the concerned users.
• Output tab: You may wish to receive the complete report as a PDF or a CSV file by email; then select 'Email recipient' as Destination and enter your SMTP address.