The Collaborative International Dictionary of English v.0.48:

Transmittal \Trans*mit"tal\, n.
   Transmission. --Swift.
   [1913 Webster]

WordNet (r) 3.0 (2006):

transmittal
    n 1: the act of sending a message; causing a message to be
         transmitted [syn: transmission, transmittal,
         transmitting]

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "transmittal":
   abalienation, alienation, amortization, amortizement, announcement,
   assignation, assignment, bargain and sale, barter, bequeathal,
   cession, communication, conduction, conferment, conferral,
   consignation, consignment, contagion, convection, conveyance,
   conveyancing, deeding, deliverance, delivery, demise, deportation,
   diapedesis, diffusion, disclosure, disposal, disposition,
   dissemination, enfeoffment, exchange, export, exportation,
   expulsion, extradition, giving, impartation, imparting, impartment,
   import, importation, interchange, lease and release, metastasis,
   metathesis, metempsychosis, migration, mutual transfer,
   notification, osmosis, passage, passing over, perfusion,
   publication, sale, settlement, settling, sharing, spread,
   spreading, surrender, telling, trading, transduction, transfer,
   transfer of property, transference, transfusion, transit,
   transition, translation, translocation, transmigration,
   transmigration of souls, transmission, transmittance,
   transplacement, transplantation, transposal, transposition, travel,
   vesting