For the name Atto see 345.i.1-2, ii.3 (cf. 320.2). Note that here there may be traces of two to three letters before Atto which could be the end of his gentilicium. What follows should be the name of the recipient and it is very strange that it too appears to begin Att-; indeed a possible reading is Attoni (though n is difficult). No doubt it is just possible that this is correspondence between two men both of whom had a fairly uncommon cognomen, but in view of the possible repetition, it is perhaps worth considering whether this is just a draft or writing-exercise in which the writer has used a name, perhaps his own, exempli gratia.
b]e[n]e [u]alere could be read but would be unexpected at the beginning of a letter (cf. perhaps 311.i.3)