Top Problems With Email Client Apps in 2026

We analyzed 1,287 negative reviews from the top 5 Email Client apps on the App Store. Here's what users hate most.

1,287
Reviews Analyzed
10
Issues Found
75/100
Opportunity Score

Top User Complaints

Ranked by frequency — how often each complaint appears in negative reviews.

#1: App crashes and performance issues

High Severity

52% of negative reviews mention this issue.

"The app always crashes and I cannot use for email."
"New update keeps crashing. If I leave the app to look at something else, it’ll freeze when I return to it."

#2: Intrusive and frequent ads

High Severity

43% of negative reviews mention this issue.

"Fullscreen ads, ads inside mails, awful."
"Every time I open the app, I have to look at an ad."

#3: Poor search functionality

Medium Severity

39% of negative reviews mention this issue.

"The search feature is worse than nothing. It fails to find specific emails."
"I’ve given this app so many chances, but the search is so bad I have to cut ties."

#4: Security and privacy concerns

High Severity

29% of negative reviews mention this issue.

"Proton Mail is not safe! They are locking people’s accounts who are activists."
"Privacy laws in Europe are a concern; Proton will likely turnover any information requested."

#5: Complex and confusing navigation

Medium Severity

24% of negative reviews mention this issue.

"The new iOS calendar design is really confusing with numbers floating all over."
"Too many choices/options just make things difficult to decipher."

#6: Email sync issues and slow updates

High Severity

36% of negative reviews mention this issue.

"Emails haven’t been working for weeks, they don’t sync across devices."
"App doesn’t update; I have to refresh manually multiple times."

UX Pain Points

Design and usability issues driving negative reviews.

Complicated swipe gestures

Inconsistent email threading

Difficult text selection and editing

Slow loading of emails and attachments

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