An effort to spread bulk mail deliveries more evenly might have hit an obstacle.

The Postal Regulatory Commission has waived a caution flag over a plan by the United States Postal Service that would attempt to spread the amount of bulk mail being delivered to the nation’s homes over the current six-day delivery week.

Too much standard, or advertising mail, is being presented to the Postal Service for delivery on Mondays, the USPS told the commission in a petition filed Dec. 27.

But the Postal Service’s plan for “standard mail load leveling” created a firestorm of opposition from big mailers.

In a March 26 ruling, the PRC said it found that USPS testing of the idea produced “inconclusive” results. It also expressed concern about the lack of support for the idea from big mailers.

The opinion was an advisory ruling, but the commission strongly urged the USPS to undertake more testing before implementing the changes.

In its petition, the Postal Service said it had determined that “it is necessary to take steps to level the load on the [mail] network now to help reduce current and future costs.”