# MailCat

> IMAP email client for automated categorization and spam filtering. (iPhone/iPad app by Seimitsusakufu LLC.)

- Source: https://appshunter.io/ios/app/mailcat/id459361669 (this page in markdown: same URL + `.md`)
- Developer: [Seimitsusakufu LLC](https://appshunter.io/developer/459361672)
- Category: Utilities
- Price: $3.99
- Rating: 1.00/5 from 1 App Store ratings · 3 written reviews indexed
- Age rating: 4+
- Requires: iOS 16.6 · 4 MB
- Languages: American English, Japanese
- Released: 2011-09-01
- Data updated: 2026-06-05
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/mailcat/id459361669/reviews.md

## What is MailCat?

■MailCat is a Mail Categorizer: 
MailCat is a Mail Categorization App.
 MailCat has two kinds of categorization method --- a machine learning categorization and a rule based categorization.
MailCat can filter out spams from the incoming mail messages by the machine learning categorizer,
and move mail messages to the specified mailbox by rules.
MailCat has no mail sending facility and has only support for IMAP. 
POP/SMS/MMS are not supported. 

■How to connect to an IMAP mail server: 
To connect an IMAP mail server, 
just specify your full email address as your login name(username) and the password you log in to your account. 
If you don't know your login name/password, contact an organization or personnel in charge of the IMAP mail server to get a hostname, user id(name), password. 

■Basic operation: 
* Pull down to Refresh/Long Press to reload&spam filtering
* Push up to download older mails at the bottom of message lists
*Tap/Swipe to switch accounts
Tapping/Swiping the navigation bar of the Mailbox list switches the account if multiple accounts are available.
* Tap/Swipe to move around mailboxes (among 'Quick View List') 
* Move/Delete/Mark mail messages by the toolbar on the navigation bar 
* Tap/Swipe the navigation bar to turn over mail messages
* Add a mail to the blacklist/spam learning data by swiping
*Tap a Tab bar to  switch the rule view.
There are 4 views to show the rules for ‘Sender’, ’Subject’, ‘Message’, ‘Compound’.

■Spam filtering: 
MailCat generates a spam filter by learning from spam and ham messages in INBOX. 
Just follow the steps, you can have your own spam filter. 

1. Tap 'Edit' button in Monitor. 
2. Pick up several mail messages by tapping each table cell. 
3. Tap "SPAM" button on the command bar. 
4. Likewise pick up mails, and "HAM" button on the command bar. 
5. "Pull down to Refresh" or "Long press on the navigation bar" triggers Machine learning, then a spam filter will be generated. 
6. Repeat the steps(1-5) until the number of spams and hams reaches about 16. 
7. After learning 16 spams and 16 hams, MailCat starts judging which mail is spam or not. 
8. Check the filtering result on Monitor. 
9. Correct errors and 'Pull down to Refresh" or "Long press( 2sec) on the navigation bar", re-learning starts and your spam filter gets smarter. 

Repeat the steps(8-9) until no errors are found. 

■Mail Rules: 
There are 4 conditional fields for mail rules --- sender, subject, message, compound.
Mail rules are only applied for 'INBOX'.
To edit or create a mail rule, tap 'Edit' button on the Mailbox list. The selection menu appears, choose 'Rule'. Mail rules for ‘Sender’ will appear. 
Tap a Tab bar to switch a view .

■Other usage: 
Please visit support page. 
http://www.seimitsusakufu.com/iOS/mailapps/en/support.html

■Support: 
To get a further support , contact through the following mail address. 
support_seimitsu@jcom.home.ne.jp

## Key features

- Machine learning spam filtering
- Rule-based email categorization
- IMAP account support
- Move emails to specified mailboxes
- Blacklist and spam learning data
- Multiple account switching

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/mailcat/id459361669/reviews.md

### 1/5 — Cannot logon to POP3 account!  Please update.

*2013-03-12, version 1.2*

I purchased this for work since I receive a lot of spam. However, it will not log on to the POP server no matter what I do. The default mail client does, so it's clearly a program failure.

### 1/5 — Not satisfied

*2012-08-30, version 1.1.0*

As categorizer it's okay but it DOES NOT act on Spam. It needs a feature that will move spam to spam folder. Not downloading mail to the iPhone is simply not enough.

### 3/5 — Poor instructions - Better available

*2011-12-12, version 1.0.6*

OK, Finally got it working some. When I posted earlier review, a reference to better instructions appeared - That helped a lot. 
Still testing ability to categorize based on email internals. We'll see.

## Frequently asked questions about MailCat

### What is MailCat?

MailCat is a mail categorization app that uses machine learning and rule-based systems to filter spam and organize incoming emails. It supports IMAP accounts and allows users to move messages to specific mailboxes.

### How does MailCat's spam filtering work?

MailCat generates a spam filter by learning from spam and non-spam messages you identify. By marking emails as 'SPAM' or 'HAM', the app's machine learning model becomes smarter over time, improving its filtering accuracy.

### What types of email accounts does MailCat support?

MailCat exclusively supports IMAP mail servers. It does not support POP, SMS, or MMS.

### How do I set up an IMAP account in MailCat?

To connect to an IMAP server, you need to provide your full email address as the login name and your password. If you don't have this information, contact your IMAP mail server administrator for the hostname, user ID, and password.

### Can I send emails with MailCat?

No, MailCat does not have a mail sending facility. Its functionality is limited to receiving, categorizing, and filtering emails from IMAP accounts.

### What are the rule-based categorization options in MailCat?

MailCat offers four conditional fields for creating mail rules: sender, subject, message, and compound. These rules are applied to emails in your INBOX to help automate organization.

### What devices is MailCat available on?

MailCat is available on iPhone and iPad devices.

### How often is MailCat updated?

The latest version of MailCat is 1.6.0, which was last updated on November 25, 2025. Updates typically address bug fixes and feature enhancements.

## Version history (last 5 releases)

### 1.6.0 — 2025-11-25

Corrections are made  to ensure compatibility with iOS 26.

### 1.5.9 — 2022-09-15

*Improvement & bug fix

1. Measures to cope with  iO16
    Bugs to be expected under iOS16 are fixed

2. iPhone notch support, until now the screen has been cut off in landscape mode.

### 1.5.8 — 2021-09-19

*Compatible with iOS15

*Bug fixes
1. Once it crashes, the app will not launch again.
2.When rule filtering is enabled, receiving mail might cause an infinite loop. 
3.Flag processing when receiving mail might not be handled correctly.
4. Some icons are not displayed in dark mode.
5. In mail search, if you enter a search string, delete the string, and then enter another string, the search result will be wrong.
6.When viewing a mail displayed by mail search, if the mail is an HTML mail with embedded external images, the mail will not be displayed correctly.

### 1.5.7 — 2021-04-01

Improvement
1.Improved error handling when account reconnection fails.

Bug fixes
1.  In some cases, fails to parse an email and crashes
2. Occasionally fails to display the subject of a mail
3. Occasionally crash on message download for multiple accounts.
4.  Other bugs

### 1.5.6 — 2020-09-22

* Some of snap shots in the online help are not latest.
Improvement
1. Measures to cope with  iO14
    Bug fixes to be expected under iOS14

Bug fixes
1.  Snippets might not be displayed with some mails
2.  Fail to parse an email with a certain multipart form.

Others、the following features are suspended because of its instability.
1. Learning&Rule data sharing through iCloud
2. Section display in the mail list screen
3. Google OAuth2.0

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## More apps by Seimitsusakufu LLC

- [MailKit-mail filter](https://appshunter.io/ios/app/mailkit-mail-filter/id550777297)
- [SpamBlocker](https://appshunter.io/ios/app/spamblocker/id570617592)

All apps by Seimitsusakufu LLC: https://appshunter.io/developer/459361672

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-05.*