Postal inspectors have issued a warning to residents to take extra precautions with their mail between now and about mid-July.

The time period coincides with the time a large number of income-tax refund checks are being sent out by the Treasury Department and always has been a prime time for mail thieves, according to postal officials.

Many mail thefts occur around the first three days of each month because of the large number of annuity and public assistance checks mailed. They tend to increase even more during the spring when many people in the community are receiving tax refunds, officials said.

Postal inspectors offer the following advice to residents:

* Make sure the mailbox is secure and in good condition.

* If you have an apartment-type mailbox, make sure the lock works and keep it locked.

* Remove mail from the box promptly.

* Notify the post office and mailers immediately of any change in address.

* Notify police and postal inspectors promptly if mail is stolen.

* Watch for the letter carriers and keep an eye on postal vehicles parked in the neighborhood. If anyone tampers with the vehicle or follows the carrier, call the police immediately and postal inspectors at 523-2551.