[User Concern] User cannot send an email to a certain email address using FlowCrypt android app

[martgil]

Description:
A user cannot send an email to an email address when using the FlowCrypt android app while sending the message using Gmail web app works.

Additionally, the email address the user trying to reach to was under of an email forwarding service called 'AnonAddy' (https://anonaddy.com/), a free and open-source anonymous email forwarding service.

Technical details:
The email composes of special characters used for email filtering such as +, = and sometimes .

Scenario:
Email Address #1: mail+demo=domain.com@email1.anonaddy.me
Email Address #2: mail+account=domain.com@email2.anonaddy.com

Using the Gmail web app, I tried to send an email to both of these addresses.

I have a successful attempt at sending an email with recipient Email Address #2 and a failed email on Email Address #1 and returns the following error message:

I tried to do the same thing on the FlowCrypt android app v.1.2.7 and I get the following error for both of the email addresses:

This prevents the user from sending an email to addresses with "complex" but a valid email addresses.

I would love to hear your thoughts about it. Thanks!

References:
https://mail.google.com/mail/u/1/#inbox/FMfcgzGmthprpZPNVdpkdkPfCmmfCQjv

[github-actions]

There were 2 email addresses found in the above comment. Please:

1. Click three dots -> edit to remove the email addresses.
2. Click edited in the comment header, and click on the previous revision of the comment.
3. When viewing the old revision with an email in it, click options -> delete this revision from history.

[github-actions]

There were 2 email addresses found in the above comment. Please:

1. Click three dots -> edit to remove the email addresses.
2. Click edited in the comment header, and click on the previous revision of the comment.
3. When viewing the old revision with an email in it, click options -> delete this revision from history.

[DenBond7]

We use the following pattern (a common approach in Android) to match valid addresses

public static final Pattern EMAIL_ADDRESS
        = Pattern.compile(
            "[a-zA-Z0-9\\+\\.\\_\\%\\-\\+]{1,256}" +
            "\\@" +
            "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
            "(" +
                "\\." +
                "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" +
            ")+"
        );

@martgil Do you think we need to switch to using something smarter? We can use for example

flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/util/BetterEmailAddress.kt

Line 47 in 3d76f42

private const val VALID_EMAIL =

[IvanPizhenko]

There is class BetterInternetAddress in the flowcrypt-enterprise-on-prem, which is more comprehensive. I suggest copy it into Android app.

[martgil]

Sorry for the late reply sir @DenBond7.

I'm not really good at regex so I had to put those two regexes (proposed, current) patterns to a test so that I have a better understanding of it.

I can confirm that the current one doesn't match the complex email address. The proposed one is very good.

[DenBond7]

flowcrypt-android/FlowCrypt/src/main/java/com/flowcrypt/email/extensions/kotlin/StringExt.kt

Line 162 in 3d76f42

fun String.isValidEmail(): Boolean {

This method accepts mail+account=domain.com@email2.anonaddy.com

[github-actions]

There were 1 email addresses found in the above comment. Please:

1. Click three dots -> edit to remove the email addresses.
2. Click edited in the comment header, and click on the previous revision of the comment.
3. When viewing the old revision with an email in it, click options -> delete this revision from history.

[DenBond7]

I'm closing it. #1898 fixed this issue.