Comparison

Polymail vs CosmoSia

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

Head to head
About

Polymail

This app acts as an email command center for professionals, offering features like real-time open tracking, scheduled sends, and message snoozing. It helps users manage their inbox efficiently for sales, fundraising, and deal-making.

Highlights
  • Real-time open tracking
  • Scheduled email sends
  • Snooze messages
  • Swipe actions for organization
  • Contact data and social context
  • Templates and reminders
  • Attachment and click tracking
Features
Read full description

The most important lever in your GTM stack is still your inbox. Polymail is the email command center trusted by founders, operators, and dealmakers for GTM execution, follow-up, and live engagement intel. - Track opens in real-time, per recipient - Schedule sends for perfect timing - Snooze messages to read later - Organize faster with swipe actions and tags - Surface rich contact data and social context - Save time with templates and reminders - Stay in flow across desktop, mobile, and web - Works with Gmail, Outlook, and more Whether you're raising a round, closing a pilot, or keeping your dealflow warm—Polymail gives you leverage where it matters most: the inbox. Join 10,000+ users who use Polymail to move faster, follow up smarter, and close more deals. - Unlimited email tracking - know exactly when and by whom your messages are read. - Snooze emails to be read later, when you need them. - Schedule emails to automatically be sent later - whenever you want. - Calendar integration makes it easy to schedule meetings over email. - Detailed contact profiles give you everything you need to know about who you're emailing. - One-tap unsubscribe removes unwanted spam in an instant. - Attachment and Click tracking - get notified when your recipients download your attachments or click on your links. - Activity Feed - see all your message tracking activity in a real time feed! - Quickly organize your inbox with customizable swipe actions. - Push notifications and background mail syncing keep your inbox always up to date. - Unified inbox and search across all your accounts. "Polymail is the first mail app I genuinely love" - Matthew Hussey, Editor-in-Chief of The Next Web

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

Polymail4 screens
CosmoSia4 screens

Verdict

The call

The clearest difference is review sentiment: Polymail at 63% against CosmoSia's 18%. Polymail also leads on rating (3.9 vs 1.0) and in-app purchases (none vs 1). On price, update cadence, monetization model 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. Polymail asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Polymail holds the better App Store score, 3.9 against 1.0. That said, the two scores are not equally well evidenced: Polymail has 86 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 63% of Polymail's written reviews are positive against 18% of CosmoSia's.

UpkeepUpdate frequency

Polymail ships an update fortnightly, CosmoSia every 3 weeks. The most recent releases landed on November 6, 2026 and November 3, 2026 respectively.

Scorecard5 real differences · 5 level
Polymail versus CosmoSia: the parameters behind the verdict, then further details
ParameterPolymailCosmoSia
PriceFreeFree
Rating3.9 (86 ratings) — better1.0 (1 ratings)
Positive reviews62.9% of reviews — better17.9% of reviews
Number of ratings86 — better1
Update frequencyFortnightly — betterEvery 3 weeks
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree with in-app purchasesFree with in-app purchases
DevicesiPhone, iPad — betteriPhone
Requires iOS16.016.0
Further details — not scored
Size40 MB219 MB
Age rating4+4+
DeveloperPolymail, Inc.ACCESS CO., LTD.

Customer experience

Polymail

All ratings86 ratings
Positive70.9%
Neutral2.3%
Negative26.7%
Written reviews859 reviews
Positive62.9%
Neutral10.4%
Negative26.8%

CosmoSia

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

Bugs and requests

Polymail

Reported bugs

4 issues
  • Frequent app crashes and freezes
  • Unread email count not syncing properly
  • Deleted emails reappearing in inbox
  • Issues with email attachments and formatting

Requested features

4 requests
  • Customizable email templates
  • Advanced email organization tools (e.g. flags, categories)
  • Support for more email providers (IMAP, Exchange, etc.)
  • Improved mobile app stability and performance

CosmoSia

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Polymail

No in-app purchases

1 purchases

CosmoSia

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

Questions

Is Polymail free?
Polymail 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, Polymail or CosmoSia?
Polymail is rated higher. Polymail averages 3.9 out of 5 from 86 ratings, while CosmoSia averages 1.0 from 1 ratings.
Do Polymail or CosmoSia have ads?
CosmoSia shows ads; Polymail does not.
Which is updated more often, Polymail or CosmoSia?
Polymail ships an update fortnightly, and CosmoSia every 3 weeks. Most recently, Polymail was updated on November 6, 2026 and CosmoSia on November 3, 2026.

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