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Training on NKDA-Architecture. Dated 13 NOV 2024 - Tetra Support Staff - NARENDRA[edit]
Video summary: Detailed architecture walkthrough (video titled "NKDA-Architecture") of a multi-site Zimbra Network Edition 10.0 mail deployment across three locations (Hyderabad, Kota, Jetsi), migrated from an earlier RainLoop/Rainmail setup. Each site runs redundant physical mail servers (MTA + LB + mailbox pairs in a PCS/DRBD HA cluster, shared NAS storage, automatic failover) plus a dedicated archive server that every user's mail is copied to. Inbound mail flow: KSMG gateway (spam/rule filtering) -> IMSVA (inbound/outbound scanning and per-domain/account rules) -> Postfix daemon -> MTA -> mailbox. Only the Hyderabad servers have direct internet mail access; Kota and Jetsi route all outbound mail through Hyderabad's MTA. Covers an "ANet" gateway used only for a set of internal-only domains (with a documented bypass procedure -- commenting those domains out of the MTA's transport file -- if that gateway goes down), quota tiers assigned by job grade/designation, scripted user creation that auto-provisions the matching archive account, a 90-day password rotation policy, blocking password-protected PDF attachments from being delivered, and the daily check needed on DRBD-based sites (Kota/Jetsi) to confirm primary/secondary storage sync hasn't fallen behind, since a failover during incomplete sync causes real data loss.