Karachi - Post Report Question and Answers
How do you send and receive your letters and package mail? Are local postal facilities adequate?
USG employees are able to use USG-issued mailing addresses to send and receive mail at the Consulate. The transit time for snail mail can take anywhere from seven to twenty-one days from CONUS to Karachi. Mail delivery can be delayed or suspended due to the current security situation in-country. - Aug 2015
Through a special U.S. Government service. I don't know much about Pakistan post, as most letters/items I receive locally are delivered by courier services. - Jun 2014
DPO (same as APO or FPO). Note: Mail is not very reliable (especially outgoing mail). Incoming mail seems to often arrive missing items or in a severely battered condition, and outgoing mail can take anywhere between 2-8 weeks. - Mar 2013
DPO (like APO/FPO) - Sep 2011