Baseball cards have a somewhat ambiguous status when it comes to being mailed as media mail. Media mail is a specific USPS mailing class that offers cheaper postage rates for certain qualifying printed materials. The exact status of baseball cards under media mail policies can depend on factors like the condition and contents of the cards being mailed.

To begin with, it’s important to understand the criteria that the USPS uses to determine whether an item qualifies as media mail. According to the official USPS domestic mail manual, media mail rates can be used for “printed items consisting solely of printed textual or pictorial matter.” This includes books, catalogs, directories, periodicals/magazines, and other printed educational materials. Media mail has restrictions and cannot be used for personal correspondence, personal messages, or items with personal information.

When it comes to sports cards like baseball cards, some key determining factors for media mail eligibility include:

Condition of cards: Singled cards or loose items would not qualify, as media mail is intended for materials “bound together.” Cards that are in protective plastic sleeves or sealed in packs/boxes would have a stronger case to argue they are “bound together.”

Advertising/information content: For cards to qualify, they need to have substantial informational or educational content beyond just images/stats. Cards with player bios, team histories, stats, or other baseball-related facts/trivia would argue they are sufficiently “printed textual or pictorial matter.”

Sales/resale purpose: Media mail is not intended for mailing of items solely for the purpose of resale/commerce. Mailing cards as part of a personal collection, as a gift, or for educational purposes would align with media mail goals. Mailing cards solely to resell them would not qualify.

Rarity/value of cards: Mailing rare/valuable individual cards could be viewed as an attempt to use the discounted media mail rate for a non-qualifying purpose. Higher-value singular cards may be more difficult to argue as media mail.

So in borderline cases, USPS employees make judgment calls. While some postal workers may accept properly packaged baseball cards as media mail, acceptance is not guaranteed and could depend on the specific contents and circumstances of the mailing. The rules for media mail can also change over time at the USPS’ discretion.

If a sender wanted the strongest case to argue their baseball card mailing qualified as media mail, some best practices they could follow include:

Ensuring cards are sealed in protective plastic sleeves, binders/books with multiple cards visible, unopened factory packs/boxes, or securely taped/bundled piles to demonstrate being “bound together.”

Including cards from multiple teams and player eras to show the educational/historical value beyond singular objects.

Providing information about the teams, players, stats, dates or anything else substantively printed on the cards themselves or accompanying the package.

Mailing as part of a personal collection transaction (like trade) rather than a commercial re-sell purpose.

Avoiding mailing rare, valuable singular cards which could appear intended for commerce rather than education.

Clearly labeling the package as “media mail” or “printed educational materials” and including a description of the cards.

Even with best practices, baseball cards still exist in a postal gray area and acceptance cannot be fully guaranteed. And mailing misclassified items as media mail runs intentional or unintentional risks, as the USPS does monitor for such issues. An alternative is to simply send at the appropriate parcel or package rate but forgo any media mail discounts.

In the end, there are good arguments on both sides regarding whether baseball cards should or can legally qualify for media mail rates. Because of extensive edge cases and judgment calls involved, this will likely remain a somewhat debatable issue without a fully clear-cut official policy from the USPS. For borderline cases, media mail acceptance of cards would depend on specific contents and how they are presented and described.

While not definitively confirmed as eligible, there are rationales that could support mailing properly prepared baseball card packages or collections as media mail in many non-commercial situations. Qualification cannot be assured, acceptance depends on discretionary USPS rulings, and compliance risks always remain. For frequent mailings, especially those with possible sale intent, standard parcel rates may provide more predictable service.