Editing Training 2022 Linux team/ (section)

==Training on Mail Sending & Receving Problem & Bouncing Problem Part-4 . Dated 05 Feb 2022 - Tetra Support Staff - Biswajit Banerjee==

{{#ev:youtube|2k6IQMwCyjw|640}}

'''Video summary:''' "Training Sending,Recieveing Bouncing part4" -- continues the series, focused on discovering how outbound mail is actually routed for a given customer and diagnosing outbound-specific delivery problems. Demonstrates checking a live Postfix config to see whether a relay host is defined (its presence/absence in the config tells you immediately whether mail leaves the box directly or via one of Tetra's relay servers), using Pahwa as a live example of a client currently routing through Trend Micro's cloud gateway with a known ongoing issue affecting Microsoft-destined mail specifically. Reiterates the ~4-5 day log retention limit on Zimbra's rotated mail logs as a hard constraint on how far back an issue can be traced. Introduces "CBPolicyd" (Postfix's policy daemon) as the mechanism controlling sending restrictions on the relay servers -- covering things like greylisting and per-domain/per-user sending quotas or rate limits -- and explains that a customer hitting an undocumented sending restriction (e.g. exceeding an outbound quota) is a real, if less obvious, cause of "my mail isn't going out" tickets; points to internal wiki documentation covering the relay servers' CBPolicyd deployment for anyone who needs to go deeper on that topic (called out as a separate, more involved topic not covered fully in this session). Session ends with the presenter noting time is up and to continue in the next part, having covered outbound relay discovery and policy-based blocking as the two main outbound-specific diagnostic angles beyond what was already covered in Parts 1-3.