The informal style is in contrast commonly used for e-mails between friends The e-mails can sometime be very short and include personal news,funny comments,etc. The language used is close to speech,so everyday words and conversations expressions are used. The correctness of grammar is not important,and some words can be omitted ('hope you're well' for ' I hope you're well',etc. ) There are uses of emoticons and abbreviations
pls for please, imo for in my opinion etc