Compostable mailers are shipping packages that degrade into elements like water, carbon dioxide, and plastic-free organic waste. They stand in contrast to traditional non-compostable shipping mailers that are often made of petroleum-based plastics.
As ecommerce grows, so does packaging waste, and customers are paying attention. According to The Packer’s Sustainability Insights 2025 report, a survey of produce consumers found that nearly 79% called sustainable packaging “important, very important, or extremely important.” This sentiment translated directly into respondents’ purchasing behavior, with over half (54%) saying that packaging sustainability impacts their final decision at least some of the time.
Read on to learn exactly what qualifies as a compostable mailer, understand how the materials compare to traditional plastic, and explore the best eco-friendly alternatives.
What are compostable mailers?
Compostable mailers are shipping envelopes designed to break down into organic matter in a composting environment, leaving behind no toxic residues or microplastics. Unlike traditional plastic, which can persist for centuries, these mailers are built to return to the earth more quickly.
Most compostable mailers are crafted from a blend of the following materials:
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Biopolymers. Often a mix of PLA (polylactic acid, derived from corn starch or sugarcane) and PBAT (polybutylene adipate terephthalate, a petrochemical-based yet biodegradable thermoplastic).
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Plant-based starches. Materials derived from potatoes, tapioca, or corn that provide flexibility and strength.
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Recycled paper. Forest Stewardship Council (FSC)-certified fibers that are non-coated and break down easily.
How do they break down?
According to a 2026 research paper reviewing available biopolymer deterioration technologies, the degradation process occurs in four distinct stages:
1. Biodeterioration. Microorganisms attach to the surface, forming a biofilm.
2. Depolymerization. Enzymes break the chemical bonds within the polymer structure.
3. Bioassimilation. Microbes consume the resulting metabolic products for energy.
4. Mineralization. The material is fully converted into water, biomass cells, and CO2 under aerobic conditions where oxygen is present.
Types of compostable mailers
You have compostable packaging options when selecting eco-friendly mailers for your shipping needs. They include:
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Poly mailers. Flexible bags that look and feel like plastic but are made from biopolymers (e.g., corn-based PLA and PBAT).
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Padded mailers. Envelopes lined with macerated paper or expanding starch-based bubbles to protect fragile items.
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Paper-based mailers. 100% recyclable and compostable envelopes made from kraft paper or sugarcane bagasse.
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Innovative materials. Cutting-edge options include wool-lined mailers for thermal insulation, mycelium-based composites (fungal fibers), and leaf fibers or seaweed-based films.
Example of real-world compostable mailers
Ecommerce business owners have found success using sustainable packaging made from durable yet compostable materials. Anaita Sarkar, cofounder of Hero Packaging, was shocked by the sea of plastic waste generated by daily outgoing orders in her prior business. “I realized that I wanted to create something for my business that I could ship products in that kind of felt and looked like plastic, but wasn’t plastic,” Anaita says on an episode of the Shopify Masters podcast.
“To be honest, this didn’t start as a business idea,” Anaita says. “This started as a solution for my previous business. I just wanted to use packaging that was better for the environment. I knew I needed it to be beautiful. I needed it to not break down during the shipping period, but I needed it to break down in my home compost bin.”
Hero packaging creates eco-friendly mailers, tote bags, boxes, and other forms of packaging, educating other businesses and end consumers on what to do with the compostable poly mailers once they arrive. The brand uses social media and blogs to show people exactly how to cut them up into smaller pieces for home and industrial composting.
Biodegradable vs. recyclable vs. compostable mailers
Compostable, biodegradable, and recyclable materials break down differently and can be repurposed in different ways. Composting involves biodegradation. Materials break down into organic matter, which by definition means they break down into carbon compounds, along with other natural substances like water.
However, not all forms of biodegradation involve composting. Composting is a more controlled process that can minimize the escape of carbon gases into the atmosphere. Instead, the carbon can be stored in new organic substances like plants and soil. An organic material can biodegrade outside of composting, but it may release more carbon dioxide, along with non-organic residues.
While some packaging materials can only be efficiently composted in industrial facilities, mailers that are certified home compostable can efficiently break down in a standard home compost bin.
Recycling does not turn packaging back into purely natural substances. It repurposes materials for new use. You can recycle traditional poly mailers made from plastic. When these products are recycled, they are spared from the landfill.
Here’s a look at what happens to compostable, biodegradable, and recyclable mailers after they’re used:
| Feature | Compostable mailers | Biodegradable mailers | Recyclable mailers |
| Breakdown process | Requires composting conditions | Breaks down over time (less controlled) | Reprocessed into new materials |
| Time to decompose | Weeks to months (in compost) | Months to years | Doesn’t decompose—reused instead |
| End result | Organic matter (no toxins) | Can leave residues | New products |
| Infrastructure needed | Industrial or home composting systems | None specific | Recycling facilities |
| Carbon footprint | Lower (if composted properly) | Varies depending on where and how biodegradation occurs | Often lowest (with the least carbon escaping) if recycled efficiently |
| Risk of greenwashing | Moderate | High | Lower (clear standards) |
Pros and cons of compostable mailers
Companies large and small have shifted to compostable mailers produced from biodegradable materials. Here are some considerations, both positive and negative, to keep in mind:
Benefits
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Sustainability. The academic paper “Composting of Biodegradable Packaging Materials” notes that composting drastically reduces reliance on virgin fossil-fuel plastics and diverts waste from landfills.
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Branding. A 2026 study from UPrinting reveals that 77% of consumers report higher trust in brands when their packaging appears eco-friendly.
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Consumer alignment. Eco-friendly packaging directly appeals to Gen Z and millennial demographics who favor environmentally conscious brands. The same UPrinting study finds that 21% of Gen Z respondents always check for sustainability labels when evaluating packaging, while 53% have stopped buying from brands due to excessive plastic packaging.
Drawbacks
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Infrastructure Issues. “Composting of Biodegradable Packaging Materials” reports that many regions lack the industrial composting facilities required to break down certain bioplastics.
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Contamination. If a customer puts a compostable bag in the recycling bin, it can ruin an entire batch of traditional plastic recycling.
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Greenwashing concerns. Terms like biosourced or biodegradable can be misleading if the product doesn’t actually break down in realistic home environments like a compost bin. Given the scarcity of industrial composting facilities, some of these items will never properly compost.
How to choose the right compostable mailer
Not all compostable mailers are equal; choosing the right one depends on your products, customers, and logistics. When sourcing shipping mailers, look for these globally recognized seals:
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BPI (Compostable). Meets US standards (ASTM D6400) for industrial composting. Standards are administered by the Biodegradable Products Institute.
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TÜV OK Compost HOME. Guaranteed to break down in a backyard compost heap at lower temperatures. The labels are certified and managed by TÜV AUSTRIA, an independent international testing, inspection, and certification body.
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TÜV OK Compost INDUSTRIAL. Requires the high heat of a municipal facility (used by industrial composters) to disintegrate. Such items are also certified by TÜV AUSTRIA.
Best alternatives to compostable mailers
If compostable options aren’t the right fit for your fulfillment workflow, consider these sustainable packaging alternatives:
1. Recycled poly mailers. These are made from post-consumer waste, and some are 100% recycled with no virgin plastic. They are more energy-efficient to produce than many bioplastics and can be recycled at specific drop-off locations.
2. Glassine or hybrid packaging. A smooth, translucent paper that is waterproof and grease-resistant. It’s 100% recyclable and offers a high-end look. It’s a popular choice for shipping apparel and cosmetics.
3. Reusable packaging. High-durability bags or boxes intended to be returned and reused. While production costs more per unit than standard plastic mailers, they have a long shelf life and reduce negative environmental impact by 59% compared to packages that get disposed of after only a few cycles.
Compostable mailers FAQ
Do biodegradable mailers actually work?
Yes, biodegradable mailers can be remarkably sturdy, rivaling or exceeding plastic mailers in the safe delivery of goods.
What is a compostable mailer?
A compostable mailer is a shipping envelope or bag designed to break down into organic matter in a composting environment.
Is there a difference between biodegradable and compostable bags?
Yes. Biodegradable bags break down over time under various conditions, while compostable bags are designed to break down into non-toxic organic matter within a specific timeframe under composting conditions.
Does the USPS allow poly mailers?
Yes, the United States Postal Service (USPS) allows poly mailers, as long as they’re securely sealed, durable enough for shipping, and meet size and weight requirements.
