Mike Bird posted a comment on Cicero and Letter Carriers, reflecting (a little too superficially) on a single quote from Atticus 1.13:

In these letters, indeed, I am urgently pressed by you to send answers, but what renders me rather dilatory in this respect the difficulty of finding a trustworthy carrier. How few of these gentry are able to convey a letter rather weightier than usual without lightening it by skimming its contents! (Letter XVIII).

Mike said:

This would suggest that some letter carriers were not just Roman fedex delivery boys, but were responsible for reading the letters on delivery. Interesting implications for the role of Phoebe in Romans and Tychicus in Colossae!

My comments (from his blog - where there are obviously intervening comments which I haven't posted here):

1. Mike, nothing in that comment suggests your conclusion that Ciceronian letter carriers "were responsible for reading the letters on delivery". That does not follow.
2. Ah. No that is not what Cicero meant. His primary issue is confidentiality, not skim reading at the destination. 'Convey a letter' means simply deliver the letter to its recipient. The reference to lightening the letter is a humorous figure of speech referring to reading the letter. Later in this same letter (Att. I 13) he refers to the risk that a letter might be lost, opened or intercepted. He adds, 'I dare not intrust a letter on such weighty matters to such a casual nobody’s son as this messenger.'
3. I don't recall any incident where Cicero refers to including money inside a letter. I don't think that is relevant here. He is worried that the letter carrier might read a fullsome and confidential letter. In fact he is so concerned by this possibility that he won't actually write the letter he would like to write (which would have included full answers to Atticus' questions). So it is an interesting situation where the presence/absence of a letter carrier impacts the composition and the contents of the letter. Lacking a trust-worthy letter carrier Cicero has to write a shorter, less detailed letter. The implication, in this situation, would be that Cicero did not want such a letter carrier to do any more than simply deliver the letter.
   
   Cicero has another delivery problem which he mentions here and in some other letters of the period, that he is not sure where Atticus is, so can't give detailed instructions to a letter carrier.