Final answer:
The restrictive endorsement is the safest option for a check being mailed to the bank for deposit, as it ensures that the check can only be deposited into a specified account.
Step-by-step explanation:
When mailing a check to the bank for deposit, the most secure type of endorsement is a restrictive endorsement. This involves writing 'For Deposit Only' followed by the account number to which the check is being deposited, and then the endorser's signature. This type of endorsement restricts the check so that it can only be deposited into the specified account, which adds a layer of security in case the check is lost or stolen during the mailing process.
Choosing the other types of endorsements for a check that is being mailed can increase the risk of misuse. A blank endorsement, which is simply the signature of the payee, makes the check negotiable by anybody who holds it. A special endorsement, which transfers the right to cash or deposit the check to another entity, or an irregular endorsement, which may refer to less common situations such as endorsements by minors or endorsements in representative capacities, are not typically used for mailing checks for deposit.