
With the best of luck the letter could be in your correspondent's hands by that evening, taking a day and a half. Of course, it could also take quite a bit longer. Bad weather could delay all the stages, the local postmater might wait a day or two to sort the mail before sending it on, or the recipient might not come into the Boston post office for days. All these things together could mean that a week would elapse between posting the letter and receiving it in Boston.
Getting a message from one small community to another would be substantially more time-consuming, because there would be no direct mail stage connections and your letter would have to go through several different post offices and stage lines; this would take several days in most circumstances.
As for
comparisons with the present day? We've all had both good and bad experiences
with the mail, but today a huge volume of mail moves at comparatively inexpensive
rates. Back then the volume of mail per person was much smaller and postage
was, relatively speaking, much more expensive. In those terms, an ordinary
letter of the 1830s cost as much as such overnight services as Express Mail
or Federal Express do today!