The MUA formats the message in email format and uses the submission protocol, a profile of the Simple Mail Transfer Protocol (SMTP), to send the message to the local mail submission agent (MSA), in this case smtp.a.org.
Milliamp Hour (mAh) An Milliamp Hour(mAh) is a unit for measuring electric power over time. mAh is commonly used to describe the total amount of energy a battery can store at one time. It's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last.
I have been asked a few times if its OK to use higher mAh rated batteries in your laptop. The answer is yes, mAh only refers to power capacity and how many milliamps the laptop battery can deliver per hour. The more important compatibility measurement is the voltage it supplies. As long as the voltage is close it should work.