The government classifies mail fraud as a serious federal offense. The state of Texas also regards it as a severe violation of the law. It involves two parts.
The first is the creation of or intention to create a plan for defrauding a person or entity. The second is the use of the postal system or private delivery services to carry it out.
For a single instance, there is a possible prison sentence of 20 years and a maximum fine of $250,000 (for individuals) or $500,00 (for organizations) if the plot did not target a financial institution or involve a presidentially declared natural disaster. If one or both of the latter two circumstances do apply, then the penalties upgrade to up to a $1 million fine for each count and up to 30 years of imprisonment.
There do exist avenues to fight against charges. Viable defenses include negligence and lack of intent to scam others. There are also grounds for rebuttal of accusations if officials mishandled evidence, the supposed target did not sustain any losses or there is no proof to substantiate claims that the conspiracy involved the use of mail communication.
Ponzi or pyramid schemes constitute mail fraud. Stealing sensitive information from individuals by sending them fake applications or forms and committing identity theft through physical mail do as well.
Mail fraud convictions have the ability to forever impact lives, but there do exist arguments against them. Wire fraud is a completely different crime.