A dozen or so covers attest to the “franking” of mail in both the pre-stamp period and later, mostly from the 1861-65 period. Two octagonal seals are known, one each for Jammu and Srinagar. Anthony Bard chronicles an early Jammu item for 3 August 1861. Séfi & Mortimer’s account is given in this ► on-site link. Those authors report a remarkable latest date of attestation for April 1873, some seven years after the advent of the first circulars.
The Jammu Frank in dull purple, image Hellrigl, detail from the cover shown downscreen. Read as srī Raghunāth/-jī sahai ḍāk/ khāne Jambū sam/-vat 191? ~ By the grace of Sri Raghunāth, post office Jammu 18[??]. Some commentaries take that date as 1857, which we are so far unable to verify. Platts tells us that the suffix -nāth pertains to the idea of patron or protector, and is used to designate Hindu ascetics, followers of Rām.
The (rarer) Srinagar Frank in dull orange-red, image Bard. Read as srī Gadādhar/-jī sahai ḍāk/ khāne Srīnagar sam/-vat 191? ~ By the grace of Sri Gadadhar, post office Srinagar 18[??]. The word gadā is a mace or club, Gadādhar (Mace-bearer) being an epithet of Krishna. Early date: April 1862 (Bard). By the way, the translations of the two inscriptions given in Séfi & Mortimer are not correct.
The b/w image on the left, taken from plate 2 of Séfi & Mortimer, was presented tacitly as a pre-stamps franking use in black of the Srinagar seal (shown right). Though the inscriptions are the same, namely munshī ḍāk Srīnagar ~ Official Post Srinagar, to our eye the implements are clearly different. Notice particularly the respective renderings of ḍāk in the lower-right sector.
Jammu franking on a Srinagar-bound letter dated possibly 2 sha'ban 1279 ~ 23 January 1863, consistent with the arrival notation interpreted as 18 māh māgh 1919 ~ 29 January 1863, a six-day journey in winter. ‘Kashmir’, understood as Srinagar, can be seen in the top line, and az khāss jamūn figures in at the lower-right. Collection Hellrigl.
Another Jammu franking on a Srinagar-bound letter. Despatch dating possibly 3 māgh 1918 ~ 14 January 1862. Top right of reverse is Srinagar, and top left of front is az jamūn.
The two examples shown above are not javab covers. It is important to note that several of the extant franked covers are indeed of that category (ref. Sturton Sale catalogue).