Links: mailing lists
Mailing lists and groups tend to do more fic-posting and fic C&C, than chatting (but there's no rule against it). Just like mailing lists, groups send or post group e-mails, except groups also have server space for the members to upload files.
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credits

Zel-Lina Shrine
Ruby Sapphire
mysticdragon3's answer to the shutdown of Listbot mailing lists. Mostly for Z/L fanfics (and pics). A moderately-sized group.
lina_zelgabunny
"Simply, an ML for the fans of the Lina and Zel pairing. Post fics, images, whatever your heart desires."
SlayersMania - The Fanfic Collective
"This is a group dedicated to the exchange of fanfiction about our favorite anime series, Slayers! Feel free to join in!" When Listbot shut down, the massive zellinaxeros mailing list moved here. Not all Z/L, but many members are. Equal parts fanfic, pics, and chat.
Lina/Zelgadis Fanfiction Mailing List (Lina/Zel ML)
"A mailing list for Slayers fanfiction with a Lina/Zelgadis bias." Owner: Relm Wanderer. Another reaction to the Listbot shutdown.

CREDITS

If there's someone I'm forgetting to give credit here, please e-mail me. I am in no way making money off of this stuff!
  • "The Slayers" is the product of Software Sculptors, Tokyo TV, Enoki Films Co., Ltd., Monthly Dragon Magazine, Weekly Comic Dragon, Fujimi Books, Hajime Kanzaka, Rui Araizumi, and Kadokawa Publishing Co., Ltd.
  • The layout and altered pics are by mysticdragon3