TL;DR
Temporary email and ProtonMail are both used by privacy-conscious people. They are different tools solving different problems. ProtonMail is a...
Aspect
Temporary Email
ProtonMail
Purpose
Nukemail provides disposable, single-use communication. You receive one or a few emails before the address ceases to exist. It isn't built for anything long-term. The disposable nature is the core feature because it keeps your identity out of databases.
Permanent and private email. ProtonMail is built to be your primary or secondary email provider for years. You build your digital identity around it. It replaces Gmail or Outlook as your main communication tool.
Encryption
There is no encryption. Emails are stored in plain text on the servers for the temp email service. Anyone with server access can read them. This works fine for verification codes but it isn't safe for sensitive communication. The short lifespan of the inbox helps lower this risk.
ProtonMail offers end-to-end encryption for emails between users. It provides zero-access encryption for every stored email. ProtonMail can't read your inbox even if compelled. It's the gold standard. That's their core value proposition.
Account Required
No account. No personal information. Completely anonymous access. You can use temp email from a public computer without leaving any trace of your identity.
You need an account. ProtonMail doesn't need a phone number for signup like Gmail does but you create a username and password. Add an optional recovery email. The signup collects minimal information to keep your account persistent.
Sending Email
Cannot send emails. Receive-only. This is by design. Temp email is a catcher's mitt, not a full communication channel.
Full sending and receiving. Calendar, contacts and drive integration. ProtonMail is a complete productivity suite comparable to Google Workspace or Microsoft 365, but with end-to-end encryption.
Trust Model
Minimal trust is needed because these emails are disposable. Even if the temp email service is compromised, nothing of value is lost since you never sent anything important to that address. You're just trusting the service with verification codes that expire in minutes.
You need to trust them. You're giving ProtonMail access to your sensitive communication for years. Proton is based in Switzerland and uses open-source clients and independent audits to earn that trust. They have operated since 2014 with a clean track record.
Website Acceptance
Websites often block disposable email addresses. This is the top annoyance with temp email. You can't use the domain on your chosen site. It's frustrating.
ProtonMail domains like protonmail.com and proton.me are accepted almost everywhere. Websites treat them as legitimate email providers. No blocklist targets ProtonMail because it is a real and permanent email service used by millions of people.
Cost
Free for basic use. Premium tiers available on some services for extended duration and features, typically $3-9/month.
The free tier includes 500MB of storage and basic features. Paid plans cost about $4 per month for extra storage, custom domains and more email addresses. The Proton Unlimited plan bundles VPN, Drive and Calendar for about $10 per month.
Mobile Apps
Most temp email services are web-only. Some have mobile apps but they are usually low quality. NukeMail works well in mobile browsers without requiring a native app.
Well-designed native apps for iOS and Android. ProtonMail's mobile experience is polished and on par with Gmail or Outlook. The apps support biometric unlock and notification management.
Verdict
These tools aren't competitors. They do different jobs. ProtonMail is your private and encrypted long-term email home. Temporary email is the disposable glove you put on before touching something you don't want on your hands.
Use ProtonMail for personal communication, sensitive accounts and anything you want to keep private long-term. Use temporary email for throwaway signups, one-time verifications and situations where you don't want to give out a real address. Don't even use your ProtonMail one for those sites.
The best privacy setup for most people includes both a private email provider like ProtonMail for important correspondence and a temp email service for the rest. These two tools protect different aspects of your digital identity.
Proton owns SimpleLogin, an email alias service. If you're a Proton subscriber, you get SimpleLogin premium included. This gives you persistent aliases to go with your encrypted mailbox. Use this alongside temp email for your truly disposable needs and you have the full privacy spectrum covered.
Some people think you should use ProtonMail for throwaway signups because it's private. ProtonMail protects your email content through encryption. Your ProtonMail address itself becomes a permanent identifier in every service database though. Nukemail avoids creating any persistent identifier at all. That is a different and complementary form of privacy protection.