Error messages and security concerns

What is considered good practice for application security wise when returning errors from a backend API?

I have inherited a project with a lot of technical debt, which I intend to improve.

One noticeable problem is that error codes are not informative at all. Sometimes it gives a 500 “error”, with no further. Sometimes it gives a 200 with an error in the JSON. Sometimes it returns a 403 not authorized which is nicer.

I want to make debugging easier, so giving more information in the error would be useful, but I wonder if there are security considerations to take into account when returning more information in error responses.

Are codes considered better than informative messages? (Seems like security through obscurity).

warning messages – Some of the functions have zero differential order

I am trying to solve the following system of differential equations, but Mathematica (11.3) complains that

NDSolveValue::pdord Some of the functions have zero differential order

I do not understand this message since all of the functions appear with their derivatives in the equations.

Here is the code:

(Rho)0 = 1;
M = 1;
eq1 = D(m(t, r), r) - 4 Pi (Rho)(t, r) R(t, r)^2 D(R(t, r), r);
eq2 = D(m(t, r), t) + (4 Pi)/3 (Rho)(t, r) R(t, r)^2 D(R(t, r), t);
eq3 = D(R(t, r), r, t) - D(R(t, r), t) D((Nu)(t, r), r) - 
   D(R(t, r), r) D((Lambda)(t, r), t);
eq4 = D((Rho)(t, r), r) + 1/4 (Rho)(t, r) D((Nu)(t, r), r);
eq5 = Exp(-2 (Nu)(t, r)) (D(R(t, r), {t, 2}) - 
      D((Nu)(t, r), t) D(R(t, r), t)) - 
   Exp(-2 (Lambda)(t, r)) D((Nu)(t, r), r) D(R(t, r), r) + m(t, r)/
   R(t, r)^2 + (4 Pi)/3 (Rho)(t, r) R(t, r);
{Ro, Ra, Ma, nu, la} = 
 NDSolveValue({eq1 == 0, eq2 == 0, eq3 == 0, eq4 == 0, 
   eq5 == 0, (Rho)(0, r) == (Rho)0, (Rho)(t, 0) == (Rho)0, 
   m(0, r) == M, 
   m(t, 0) == 
    M, (Nu)(0, r) == -(1/4) Log((Rho)0), (Nu)(t, 
     0) == -(1/4) Log((Rho)0), (Lambda)(0, r) == 
    0, (Lambda)(t, 0) == 0, R(0, r) == ((3 M)/(4 Pi (Rho)0))^(1/3), 
   R(t, 0) == ((3 M)/(4 Pi (Rho)0))^(1/3), 
   Derivative(1, 0)(R)(0, r) == 1}, {(Rho), R, 
   m, (Nu), (Lambda)}, {t, 0, 1}, {r, 0, 1})

Note: another message appears saying that the initial and boundary conditions are inconsistent, but that is another problem I have to solve later, I am more concerned with the other message at the moment.

mobile network – Intermittent failure to receive SMS and MMS messages

I noticed an issue in mid December where a few messages in a row that were sent in a group MMS were never received on my phone. A few days ago, I had the same issue with an SMS message sent to me. There may have been other instances as well that I’m unaware of. In December, my default messaging app was QKSMS. In the instance a few days ago, my default SMS/MMS app was Signal.

I’m using an Asus Zenfone 6 on Wing’s AT&T network (for those don’t know, this essentially means Wing bought AT&T contracts in bulk and is reselling them individually).

I don’t know of any issues with outgoing messages. The intermittent nature of this problem makes it difficult to troubleshoot. What steps can I take to ensure I don’t lose any incoming MMS or SMS messages in the future?

Is it possible to accept messages in Postfix that are sent to an invalid email address?

I have a Postfix server running and receiving email for “”. I am wondering if it is possible to configure Postfix to accept email for any address sent to it. For example, could I configure it to accept messages sent to Right now when I do this, the message bounces.

Sript/GUI to leech messages |


I am looking for a replacement for themaLeecher which no longer supports leeching messages from Manyvids.

I am looking to buy a script/gui/program to leech new “posts”/”videos messages” from manyvids profiles.

For example, I want to know when this updates the store with new stuff.

its pretty boring to go throut 2-3-400 profiles to check for updates – i need some sort of automatic way of doing that.

Name your suggestion for a solution and a price and I am open minded.

If you need more specifics just ask – thank you.

smtp – postfix enable sending bounce messages to sender

I currently trying to enable sending mails to the sender then the mail is undeliverable. For example the which is the MX for my.domain recieves a mail for person1@my.domain:

868942A: to=<person1@my.domain>,, delay=1.2, delays=0.95/0/0.2/0.02, dsn=5.0.0, status=bounced (host
 said: 550 Recipient denied. (in reply to RCPT TO command)) tries to deliver the mail to This host has a acl of every mail address which is allowed to send to. Because person1@my.domain is not in this list it rejects the mail. How can i configure to send a “undelivered” Mail to the sender?

I found the notify_classes configuration here but that seems to only send bounce messages to a own mail address and not to the original sender.

web app – Best practice for out-of-app notifications for in-app messages?

Platforms like Task Rabbit and Airbnb send users an email and/or text message when an in-app message is received.

What is best practice in terms of UX for how and when these out-of-app notifications (e.g. email / text message) are sent?

One strategy could be to simply send notifications every time a message is received in-app. But I wonder if that could bombard users who receive a flurry of quick notifications, especially if those notifications are via text message or email. A counter argument to that could be that many message and email clients tend to group together emails from the same sender nowadays, so the recipient may not feel bombarded at all.

I thought about more nuanced approaches, where out-of-app notifications are only sent if certain conditions are met. For example max 1 notification every 30 seconds. But I’m not sure if that’s a good idea.

So in terms of medium, frequency, and any other considerations, what are best practices for notifying users of an in-app message?

warning messages – User defined function needs to be run twice

I have a user-defined function that upon executing gives the error

$IterationLimit::itlim: Iteration limit of 4096 exceeded.

However, after I abort it and try to run it again, it runs fine. Why does it only work on the second execution? The function is very long and complicated so I am hesitant to post it here.

Is it possible to have Gmail index more mail to allow searching of older messages?

Search operators using dates are very limited to only about a year.