I like it; and I also have fond memories of the old days of BBS.
The Othernet stations are supposed to be useful community and education center magnets; so like old shared time unix systems and BBSs this makes total sense with rotated deletes and news, perhaps including the satellite delivered news about outernet as was mentioned here. Fido/NNTP echomail/news
If we are already talking BBS and local mail I also feel that adding a semi or fully automated USB stick combined fidonet/sneakernet delivery system so someone can ‘take the mail to town’ as is already a proven solution among the technical but unwired black market sneakernet in Cuba or the DPRK, again addressing the the specific access problem that Outernet is helping to solve.
If we are really looking to engineer a simple solution that NGOs can hand off to less net-savvy end users perhaps an image customized for a pocket sized ‘mailbox’; a Pi-W, case with rechargeable battery and one external USB port for rugged flash drives, an on/deliver button, several status LEDs for ready, wifi associated, undelivered mail loaded, and all mail on drive delivered at a one or several central email post office WiFi APs. Othernet could even send down new AP names and settings for the pocket portable Mailbox user to access.
Sending low value low capacity microSD cards under a sticker on postcards taking advantage of that media’s discount in most postal systems also gets us a laggy but cheap and sufficient bandwidth for a minimal community mail delivery return channel.
If the Mailbox auto delivery Pi-W gizmo is not used at least the Othernet base station can on command package an encrypted archive into a delivery file(deleted from the Othernet device when it receives a sent notification over Ka band) to be carried on a flash drive or card and uploaded to an Othernet portal page or sent to Othernet by anyone who couriers the file out by whatever means as an email attachment. A processing script at Othernet or another NGO could decrypt, parse, and send over the internet the email messages in the delivery bundle file, eventually some of those emails might just be sent back down to other stations on the Othernet.