Soo, making the calculations, there will be... ALOT, of mails
Gossip Ghoulie emails you when you meet a harbinger, defeat them, and when you lose to them, making up to 12 emails from this only, which is a lot, and take into consideration the final 4 emails for reaching Mindmaze, finishing it, entering Mrs. MEANIE's laboratories, and the final email for before you fight the final boss
Pastafiend has way less emails, only emailing you once per ending, being uhhh roughly 5 mails
The Freds have only 2 "regular" emails, but after defeating Addiction, Gossip Ghoulie gives you a tool called SPYWITHMYLITTLEEYE which lets you unlock some emails from the The Freds, Gossip Ghoulie knows about this as she's friend with REDFRED, a former Fred which has a red eye on his left, but these aren't taken into consideration