Congrats on your move to Korea — that’s a big step. Since you’re trying to figure out which virtual mailbox services are worth your time (and worth your money), here are some things I’d suggest thinking about specifically as an expat and based on what you described wanting.

Start With Mail Volume and Use Case, Not Just Price

It sounds like your primary needs are receiving new credit cards and the occasional important notice (like an IRS letter or something regulatory). That’s a pretty low volume of mail overall, but the type of mail matters — financial mail, bank/credit card correspondence, and potential tax forms all warrant careful handling.

Before you lock into a service, ask yourself:

• Will you be keeping U.S. bank accounts active?
• Are you expecting brokerage, dividend, or tax documents annually?
• Do you subscribe to anything that still sends physical mail?

Even with low volume, you still want a plan that includes enough scans and clear options for how you want each piece handled (trash, open & scan, forward).

A recent Upwork article compares features, pricing tiers, and major providers in a helpful way when weighing options:
https://www.upwork.com/resources/best-virtual-mailbox-services

When comparing plans, make sure you understand:

• How many mail pieces/scans are included
• What per-envelope overage fees are
• How international forwarding is priced

Check Deposit + Package Forwarding Options

Even though you said you mostly expect credit cards and occasional documents, the way a provider handles:

• Checks
• Packages
• Envelopes with multiple items

…really matters.

Some services only scan the front of checks or charge extra for endorsement. Others allow you to consolidate multiple packages into one shipment before sending internationally, which can save a lot on shipping fees.

Ask providers:

• Do they forward internationally directly?
• Can you request consolidation?
• Are there storage fees before forwarding?

Security & Handling Is Important

Since you’re keeping important financial mail active, you want a provider with strong security and clear procedures. There’s a big difference between mail being handled in a professional commercial facility versus a small storefront or PO box setup.

Look for providers that:

• Operate from secure commercial locations
• Restrict mailroom access
• Have formal handling procedures
• Offer tracking and documented processing

Established companies with transparent operations are usually worth paying slightly more for when it comes to financial mail.

Address Choice: State With No Income Tax

You mentioned wanting an address in a state with no income tax just to be extra safe since you’ll be earning dividends.

A virtual mailbox address alone does not establish residency or change your tax obligations. State tax residency is determined by a combination of factors like domicile, voter registration, driver’s license, physical presence, and intent — not just where your mail is sent.

If you’re seriously trying to change state residency for tax purposes, that’s something to plan carefully with a CPA who understands expat taxation. For most people, mailbox location alone does not change their state tax exposure.

Shipping From the U.S. to Korea: What You Should Know

Since you’ll occasionally forward credit cards or important documents, it’s helpful to understand how shipping to Korea works.

Documents vs. goods matter a lot. Pure documents (paper only, credit cards, bank letters, tax notices) generally move through customs smoothly and do not trigger duties.

If you forward physical goods (electronics, clothing, supplements, etc.), customs becomes more involved.

Here are the key official resources:

USPS international mail rules for South Korea (includes restrictions and customs requirements):
https://pe.usps.com/text/imm/ps_023.htm

USPS customs forms and declaration requirements:
https://www.usps.com/international/customs-forms.htm

Korea Customs Service (official import rules and Personal Customs Clearance Code information):
https://www.customs.go.kr/english/main.do

Information on Korea’s Personal Customs Clearance Code (PCCC):
https://www.customs.go.kr/english/cm/cntnts/cntntsView.do?mi=10802&cntntsId=5502

In general:

• Anything other than documents requires a customs declaration with accurate description and value.
• South Korea’s general de minimis threshold is about $150 USD for most shipments (under the U.S.–Korea Free Trade Agreement certain U.S.-origin goods may qualify differently).
• If you receive goods, you will likely need a PCCC to clear shipments. Couriers such as DHL or FedEx commonly request this.
• Courier services are faster and more secure but typically more formal in customs processing. USPS is cheaper but slower.

For your use case — mostly credit cards and financial documents — you likely won’t run into major customs issues. Just make sure:

• The provider declares items accurately
• You use tracking for important shipments
• You obtain a PCCC if you ever plan to forward physical goods

Best “Bang for the Buck” Means the Right Fit for You

Since your use case is low volume but high importance, prioritize:

• Clear control over trash/open/scan/forward
• Predictable pricing
• Secure handling of financial mail
• Reasonable international forwarding rates
• Strong customer support

Cheapest isn’t always best when your identity, credit cards, and tax documents are involved. Hope this helps!