Comparison

Email.cz vs CosmoSia

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Email.cz

Manage all your email accounts from one place with this app. Access your folders, search old messages, and send emails even when offline. It adapts to your device's dark or light mode and offers enhanced security.

Highlights
  • Unified inbox for multiple accounts
  • Offline email access and sending
  • Quick search for older messages
  • Dark/Light mode adaptation
  • Enhanced security features
  • Folder management
Features
Read full description

Your mailbox will be everywhere with you thanks to new version of Email.cz app from Seznam.cz. All your folders with messages will be right at your fingertips. Older messages are quickly accessible with search functionality. You can easily swap between your mailboxes if you have connected more than one account. Application adapts to the Dark/Light mode setting of your device. You can arrange your emails in offline mode and your messages will be sent when you have access to internet connection. App security enhancements.

About

CosmoSia

Create a personalized email address with your own domain, offering carrier-like ease of use and robust privacy features. Manage multiple email accounts, block unwanted messages, and enjoy a user-friendly interface. Ideal for those seeking a professional or custom email solution.

Highlights
  • Create custom email addresses
  • Manage multiple email accounts
  • Block unwanted emails
  • Easy setup
  • Carrier-like usability
  • Privacy-focused
Features
Read full description

Recommended for those who are considering moving away from carrier email. You can create "XX@cosmosia.email" which is as easy to use as your carrier email! Made in Japan, so you can be sure of your privacy. Make your email more fun! The long-awaited iOS version of the free email app with over 1 million users is now available! - Just tap! The all-new "Reactions" feature Get your feelings across without words: Just like in a chat, react to emails with emoji. Reaches the other person even without the app: When you add a reaction, the recipient automatically receives a clear notification email. No matter which email service they use — Gmail, docomo mail, Yahoo! Mail, and more — your "I saw it" comes through loud and clear. Stay connected like a conversation: Even in group exchanges, you can see at a glance who reacted and how, so conversations keep flowing and stay fun. - You can create your own email address! You can create your own e-mail address such as XX@cosmosia.email. You can use email addresses such as XX@cosmosia.email. The email address will be linked to your phone number like a carrier email address, so please consider this when you are thinking of moving from a carrier email address! Email address is available only when you purchase the subscription "CosmoSia Email Plan (Monthly)". We also recommend this service when you move to ahamo, povo, LINEMO, or other plans that do not include carrier email! ==================== - You can manage multiple email services at once. IMAP4 (Gmail, docomo mail, etc.) is supported.   - It is a standard email application for low-cost smartphones and MVNOs. It's easy to use, just like a carrier email, and it's popular among low-cost smartphone users! - Easy to set up Just set your email address and password and you're ready to go. Organize your mailbox now. - No more unwanted e-mails! We support a "reject list" function that allows you to prevent unwanted e-mails from entering your inbox. - Basic functions are free! The installation is free and the basic functions are free no matter how many times you use them. A predetermined usage fee is required to use CosmoSia Mail. You will have to pay for the communication charges incurred when sending and receiving emails. ==================== The following email services can be used docomo mail au-mail R mail Y! mobile mail Yahoo! JAPAN mail iCloud mail Gmail Outlook/Hotmail mineo mail so-net mail BIGLOBE mail We support the setup of many other email services. * You cannot use your UQ mobile email address (XX@uqmobile.jp). Please look forward to future updates for support of other mail services! ==================== About the trademark docomo mail is a trademark of NTT DOCOMO, INC. in Japan.

Screenshots

Email.cz4 screens
CosmoSia4 screens

Verdict

The call

The clearest difference is rating: Email.cz at 4.6 against CosmoSia's 1.0. Email.cz also leads on in-app purchases (none vs 1) and ads (none vs shown). On price, review sentiment, update cadence and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. CosmoSia sells 1 in-app purchase, starting at $2.99 per month. Email.cz asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Email.cz holds the better App Store score, 4.6 against 1.0. That said, the two scores are not equally well evidenced: Email.cz has 58 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 13% of Email.cz's written reviews are positive against 18% of CosmoSia's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Email.cz ships an update monthly, CosmoSia every 3 weeks. The most recent releases landed on November 10, 2026 and November 3, 2026 respectively.

Scorecard5 real differences · 5 level
Email.cz versus CosmoSia: the parameters behind the verdict, then further details
ParameterEmail.czCosmoSia
PriceFreeFree
Rating4.6 (58 ratings) — better1.0 (1 ratings)
Positive reviews13.1% of reviews17.9% of reviews — better
Number of ratings58 — better1
Update frequencyMonthlyEvery 3 weeks — better
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad — betteriPhone
Requires iOS17.016.0 — better
Further details — not scored
Size27 MB219 MB
Age rating4+4+
DeveloperSeznam.cz a.s.ACCESS CO., LTD.

Customer experience

Email.cz

All ratings58 ratings
Positive87.9%
Neutral5.2%
Negative6.9%
Written reviews99 reviews
Positive13.1%
Neutral14.1%
Negative72.7%

CosmoSia

All ratings1 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews39 reviews
Positive17.9%
Neutral15.4%
Negative66.7%

In-app purchases

None

Email.cz

No in-app purchases

1 purchases

CosmoSia

Subscriptions1
  • CosmoSia Mail Plan(Monthly)7 Days trial$2.991 Month

Questions

Is Email.cz free?
Email.cz is free to download, with no in-app purchases.
Is CosmoSia free?
CosmoSia is free to download, with in-app purchases available.
Which has better reviews, Email.cz or CosmoSia?
Email.cz is rated higher. Email.cz averages 4.6 out of 5 from 58 ratings, while CosmoSia averages 1.0 from 1 ratings.
Do Email.cz or CosmoSia have ads?
CosmoSia shows ads; Email.cz does not.
Which is updated more often, Email.cz or CosmoSia?
Email.cz ships an update monthly, and CosmoSia every 3 weeks. Most recently, Email.cz was updated on November 10, 2026 and CosmoSia on November 3, 2026.

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