There always been speculation of Beypore Mail as "through" since inception which isn't true as per attachment dated Mar 29 1862 (for 11 May), which says:
1. 1,2,3 GD Class Train from SA to Beypore - SA 6:15, Beypore 17:30/6:30, SA 17:45
2. CBE-Beypore (till SA-Beypore line is pending. CBE 11:45, Beypore 17:30/6:30, CBE 12:20
Pic 2&3: Between Feb-Aug 1864 MAS-Beypore is still SA-Beypore...
more... Ord, 1&2 Class attach at SA while MAS-SA is Goods!! Its slowed down to reach Beypore at 19:00 instead of 17:30 (SA ARR 18:40 instead of 17:45)
SBC inception in 1864 marked foray of: Nilgiri, Island, SBC Mail, MAS-Beypore Mail as Ord Service branched out of SA-Beypore Ord (which still exist as 3rd Class was attached in SA-Beypore Pic 4)!!
PS: Postal Letters of 1863 & Jan 1863 Experiment for P&O (Calcutta-Madras-Beypore-Bombay) already reinforced no through existence for Beypore-Mas (although SA-Beypore undoubtedly was forerunner of lot many Mails but its through CBE-MAS run will be the inaugural date as MAS-Beypore Line was through since 1862 owned by MR)!!
Pic 1: Forerunner of PTJ-Beypore/MAQ Mail as CBE-PGT Ord: 1&2 GD Class: CBE 7:00, PGT 8:40/15:15, CBE 17:00