Ease of Use – Should a message appear confirming that the user wants to leave the program when they click the Back button in an app?

I'm having trouble deciding whether to show a message in an app when the user presses the back button when exiting.

The following image shows how 9gag does this (see the message "Pressing Back to Exit" below).

I am worried that this may be annoying for some people, but I am aware that others may press the back button too many times and accidentally leave the page.

Can someone point me to research results or sources that cover this type of UX scenario?

I am interested in best practices in such situations.

How do I disable the message in Firefox: "Thank you for downloading Firefox, please help us to find out what people like you expect."

Firefox displays a message that says:

"Thanks for downloading Firefox, please help us find out what people like you expect."

I need to disable this and make sure that it never appears in the first place because my application is a kiosk application.

Better yet, make sure that such news never appears, but I would be glad to know how to get rid of this message.

Enter image description here

Thank you very much

Email – Mail failed: Return message to sender

Emails sent to a domain are never delivered and my customer receives an email with back

—– Message d & origine —–
De: Mail delivery system
Sent: October 17, 2019 14:39
Item: E-mail delivery failed: return message to sender

This message was automatically generated by the e-mail delivery software.

A message you sent could not be delivered to one or more of them
Receiver. This is a permanent mistake. The following addresses failed:


And in the appendix there is a txt file with:

Reporting MTA: DNS; us205.siteground.us

Action: failed
Final recipient: rfc822; a.cole@DOMAIN.com
Status: 5.0.0

Action: failed
Final recipient: rfc822; f.ray@DOMAIN.com
Status: 5.0.0

Any idea what's going on?

dovecot – doveadm search – define message path

I am working on a mechanism that will delete old junk / trash user emails. In addition I would like to use doveadm expunge, z.

doveadm expunge -u xxx@yyy.zz mailbox Spam SENTBEFORE 2019-10-23

This will be a "new feature" so I want to back up emails before they are deleted. Just in case. For this I can search for emails:

doveadm search -u xxx@yyy.zz mailbox Spam SENTBEFORE 2019-10-23

As a result – Doveadm gives me guid / uid. Is there an option to find the message path using this GID / UID (to make a backup copy)?
Or another way to easily back up messages before deleting them?

kali linux – FTP services for fingerprints without banner message

I want to write a Python script that is capable of fingerprinting ports on a server to identify the FTP client running on the port.

While a banner message is often displayed when connecting, this message is not reliable or can be easily removed.

Is there a tool / database, etc. that can help identify the different clients based on their behavior? e.g. While searching the source code, I noticed that the PyFTPd server used the message "I will ignore this command …" to identify this service.

I appreciate any help, as many FTP commands are supported and included in all daemons, making it difficult to find all the differences … I'm trying to make a difference


postgresql – what does this connection error message mean?

$ psql -h host db_name

psql: New process for connection could not be split: memory can not be allocated

I think I have enough free memory?

Other conditions when using jdbc:

Caused by: java.lang.IllegalStateException: Received resultset tuples, but no field structure for them
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2086)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:288)
    at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:430)
    at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:356)
    at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:168)
    at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:116)

org.postgresql.util.PSQLException: A connection could not be made using the requested protocol null.
        at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:59)
        at org.postgresql.jdbc.PgConnection.(PgConnection.java:216)
        at org.postgresql.Driver.makeConnection(Driver.java:404)
        at org.postgresql.Driver.connect(Driver.java:272)
        at java.sql.DriverManager.getConnection(DriverManager.java:664)
        at java.sql.DriverManager.getConnection(DriverManager.java:247)

  Detail: Failed on request of size 81160 in memory context "MessageContext".
java.lang.RuntimeException: org.postgresql.util.PSQLException: ERROR: out of memory
  Detail: Failed on request of size 81160 in memory context "MessageContext".