I'm apt to cherry pick subjects [as opposed to doing 'mass mailings'] to send to for a request to sign an item of mine through the mail - I don't send as much as I think I should be sending out because I've gotten lazy over the years and it is annoying how postage rates go up every couple of years.
Through the mail autograph requests are not an exact science - sometimes you get smudged, streaked autographs because of how the autographed item was placed back in your SASE [self-addressed stamped envelope].
Also, I don't worry about it too much but some subjects [like baseball players] wait until their 'fan mail' has piled up before answering it all - usually towards the end of their respective seasons and/or their off-seasons.
I sent out a small batch of requests to be mailed - most are spring training requests except for 2008 Olympians Shawn Johnson [gymnast] and Cat Osterman [softball].
Andrew Cashner c/o Chicago Cubs [spring training] - two cards
Shawn Johnson c/o training facility - an 8x10
Joey Votto c/o Cincinnati Reds [spring training] - two cards
Austin Jackson c/o New York Yankees [spring training] - one card
Koji Uehara c/o Baltimore Orioles [spring training] - one Japanese card
Kenshin Kawakami c/o Atlanta Braves [spring training] - three Japanese cards
Joba Chamberlain c/o New York Yankees [spring training] - the 2007 Beckett Rookie Rolodex issue and a card
Cat Osterman c/o DePaul Softball - an 8x10
I'll probably mail out more requests when I back from spring training - I figure I'll send more out when I see who has signed or who hasn't signed.