USPS "Forever Stamps" are considered "second-class mail," and items sent with those stamps are processed more slowly. See Example( s )
On 12 April 2007 the United States Postal Service (USPS) introduced the “Forever Stamps.” As described in a pre-launch 4 May 2006 Washington Post article, the concept behind Forever Stamps was that they could be purchased at the current rate for first-class postage, but they could be used to mail letters (without the need for additional postage) no matter how much postage rates might change in the future
Postal officials pitched the idea of creating a “forever stamp” that would be good for sending First-Class mail no matter how much — or how often — the cost of a postage stamp goes up. The announcement came on the same day that the Postal Service said it would seek to raise the price of a First-Class stamp for the second consecutive year.
The forever stamp, which would cost the same as a First-Class stamp, would provide a hedge against future postal rate increases and end the search for 2- or 3-cent stamps that usually follows a price increase.
That early news coverage explained that no matter when a Forever Stamp (also known as non-denominated postage) was purchased, it entitled the buyer to use it for first-class postage:
If the cost of sending a First-Class letter is raised to 42 cents next year, for instance, the forever stamp would be sold for that amount. If the First-Class rate then increased by 2 cents a year or two later, forever stamps would sell for 44 cents. But forever stamps purchased at the 42-cent rate still would get a First-Class letter where it needs to go.
“If you buy it, it can be used forever on single-piece First-Class letters,” said Stephen Kearney, vice president for pricing at the Postal Service.
Despite subsequent rumors that mail sent using Forever Stamps is somehow processed differently (and slower) than other mail, a USPS “Forever Stamp Fact Sheet” released at the time of the Forever Stamps’ introduction [PDF] made no mention of a separate classification or handling of letters mailed using Forever Stamp postage. A similar document found on the USPS’s web site in March 2016 reiterated that the primary difference between Forever Stamps and denominated postage was a locked-in rate. All reporting has described Forever Stamps as identical to their denominated First-Class counterparts, save for built-in protections against postal rate hikes.
One aspect of such rumors holds that items sent using Forever Stamps are considered “second-class mail,” but that category (now called “Periodicals“) applied to newspapers and magazines that were handled with a lower priority than first-class mail, not to letters and other enveloped items.
This rumor might stem from the fact that recent years have seen wide fluctuations in delivery times for first-class mail and slowdowns in the handling of all first-class mail. In December 2014 the USPS released a fact sheet [PDF] explaining that consolidation of mail processing facilities had led to longer transit times for first-class mail:
In the past 10 years, total volume has declined by more than 56 billion pieces (or 26%), First-Class Mail volume has declined 34.5 billion pieces (or 35%), and single-piece First Class Mail (primarily letters bearing postage stamps) has declined 24.4 billion pieces (or more than 50%).
In January 2015, the Postal Service changed its First-Class Mail service standards, affecting roughly 14 billion pieces of the total volume (or 9%) and up to 16% of First-Class Mail. The affected volume represents primarily single-piece First-Class Mail. The majority of this mail is being delivered in two days instead of one.
Today, total First-Class Mail is delivered in an average of 2.1 days. Prior to the service standard change, First-Class Mail was delivered in an average of 1.8 days.
On 1 February 2015, Wisconsin’s Journal Times reported that many USPS customers were unaware of the adjusted first-class mail delivery projections despite the USPS’s ongoing efforts to notify the public about them:
Facing a dramatic decline in the mail volume, the agency announced in 2011 that it would be consolidating the processing and distribution facilities and making revisions to its First-Class Mail service standards.
Those standard changes, which took place nationwide on Jan. 5, resulted in the average processing and delivery time for a piece of First-Class Mail, such as a birthday card or magazine, to increase from an average of 1-2 days to an average of 1-3 days, explained Sean Hargadon, spokesman for United States Postal Service.
Despite efforts by the U.S. Postal Service to educate the public about the adjustments, Hargadon said it’s likely that those who noticed the delays weren’t aware the changes were coming.
“First-Class Mail has dropped by more than 50 percent in the last 10 years, so we have adjusted the standard to reflect that,” Hargadon said. “With First-Class Mail, what people are used to is: ‘If I drop it today my friend will get it tomorrow.’ Well, not necessarily anymore.”
An April 2015 Washington Post article also described a slower delivery times for first-class mail (partially attributed to inclement weather during the time period in question):
In January , the Postal Service eliminated overnight delivery for local first-class letters that used to arrive the next day. Anywhere from 20 percent to half of the rest of the first-class mail sent every day now takes an extra day of delivery time.
National performance for single-piece first-class mail with 1-day, 2-day, and 3-5 day delivery standards declined throughout fiscal 2014 after a relatively good second quarter in fiscal 2013.
Postal officials have said that severe winter storms had a significant impact on performance results for many service standards, slowing trucks from driving mail to post offices or airports, where it was flown out.
In short, it is no secret that the USPS began adjusting the speed of first-class mail delivery as far back as 2011, as they restructured their processing procedures. But those adjustments were in no way linked to any purported lower priority for Forever Stamp-bearing letters, and the USPS has repeatedly explained that Forever Stamps are treated in every way as standard first-class postage.