What is Email: Definition and 185 Discussions

Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email entered limited use in the 1960s, but users could only send to users of the same computer, and some early email systems required the author and the recipient to both be online simultaneously, similar to instant messaging. Ray Tomlinson is credited as the inventor of email; in 1971, he developed the first system able to send mail between users on different hosts across the ARPANET, using the @ sign to link the user name with a destination server. By the mid-1970s, this was the form recognized as email.
Email operates across computer networks, primarily the Internet. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect, typically to a mail server or a webmail interface to send or receive messages or download it.
Originally an ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions (MIME) to carry text in other character sets and multimedia content attachments. International email, with internationalized email addresses using UTF-8, is standardized but not widely adopted.The history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973 (RFC 561). An email message sent in the early 1970s is similar to a basic email sent today.

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  1. P

    MHB Luca's question via email about a line integral....

    I am assuming that this line integral is along the straight line from $\displaystyle \begin{align*} (0,0,0) \end{align*}$ to $\displaystyle \begin{align*} \left( 5, \frac{1}{2}, \frac{\pi}{2} \right) \end{align*}$, which has equation $\displaystyle \begin{align*} \left( x, y, z \right) = t\left(...
  2. Arij

    Other Email Request: Join Research Group?

    I am sorry if this sounds very basic, but I am really troubled on what to title an email regarding a request to join a research group! Any ideas or guidelines?
  3. C

    Admissions Should I email potential advisors when applying to masters program

    Hi everyone, I'm planning to apply to a few terminal masters programs this fall, with the goal of doing a thesis option and applying to PhD programs after the masters. (I have various reasons for wanting to go this route instead of applying straight to a PhD). I know it's good to seek out and...
  4. Drakkith

    Which Windows program can help me manage multiple email accounts?

    Hey all. I've recently accumulated upwards of 5 or 6 different email accounts that I need to check and I'm having a hard time keeping track of it all. I'm looking for a good program for windows that I can use to keep track of all my accounts instead of having to open and log into each one...
  5. P

    MHB Collin's question via email about a Laplace Transform

    As the Heaviside function is a function of t - 4, that means all other terms must also be functions of t - 4. The sine function is, but the exponential isn't. However with a little manipulation, we get $\displaystyle \begin{align*} f\left( t\right) &= \mathrm{H}\,\left( t - 4 \right) \,\sin{...
  6. P

    MHB Collin's question via email about solving a DE using Laplace Transforms

    Taking the Laplace Transform of both sides we have $\displaystyle \begin{align*} \mathcal{L}\,\left\{ y'' + 4\,y \right\} &= \mathcal{L}\,\left\{ \mathrm{H}\,\left( t - 7 \right) \right\} \\ s^2\,Y\left( s \right) - s\,y\left( 0 \right) - y'\left( 0 \right) + 4\,Y\left( s \right) &=...
  7. P

    MHB Collin's questions via email about Inverse Laplace Transforms

    As the denominator is a function of s + 3, it suggests a shift had to have been utilised. As such, we also need the numerator to be a function of s + 3... Let $\displaystyle \begin{align*} u = s + 3 \end{align*}$, then $\displaystyle \begin{align*} s = u-3 \end{align*}$ and thus...
  8. P

    MHB Henry's question via email about an Inverse Laplace Transform

    It's not entirely obvious what to do with this question, as the denominator does not easily factorise. However, if we realize that $\displaystyle \begin{align*} s^4 + 40\,000 = \left( s^2 \right) ^2 + 200^2 \end{align*}$ it's possible to do a sneaky completion of the square... $\displaystyle...
  9. B

    Other Switching groups, how to email new prof?

    Suppose one was working for a Professor. Then you mutually decide that it's not a good fit. The professor has been helpful in terms of suggestions for other people to work with and you found another professor who has given you some reading material earlier. How do I email the new professor if...
  10. P

    MHB Sava's question via email about matrix multiplication

    $\displaystyle \begin{align*} A\,A^T &= \left[\begin{matrix} 3 & 0 & -4 \\ 4 & 0 & \phantom{-}3 \\ 0 & 5 & \phantom{-}0 \end{matrix}\right]\left[ \begin{matrix} \phantom{-}3 & 4 & 0 \\ \phantom{-}0 & 0 & 5 \\ -4 & 3 & 0 \end{matrix}\right] \\ &= \left[ \begin{matrix} 3\cdot 3 + 0 \cdot 0 +...
  11. P

    MHB Sava's question via email about symmetric matrices

    A matrix is symmetric if it is equal to its own transpose, so to show $\displaystyle \begin{align*} C^T\,C \end{align*}$ is symmetric, we need to prove that $\displaystyle \begin{align*} \left( C^T\,C \right) ^T = C^T\,C \end{align*}$. $\displaystyle \begin{align*} \left( C^T\,C \right) ^T &=...
  12. P

    MHB Sava's question via email about integration with partial fractions.

    As there is a repeated root, the partial fraction decomposition we should use is: $\displaystyle \begin{align*} \frac{A}{x - 1} + \frac{B}{\left( x - 1 \right) ^2 } + \frac{C}{x - 2} &\equiv \frac{x^2}{\left( x - 1 \right) ^2\,\left( x - 2 \right) } \\ \frac{A\,\left( x - 1 \right) \left( x - 2...
  13. P

    MHB Question via email about complex numbers

    We should note that we can write any complex number as $\displaystyle \begin{align*} z = r\,\mathrm{e}^{\mathrm{i}\,\theta} \end{align*}$ where $\displaystyle \begin{align*} r = \left| z \right| \end{align*}$ and $\displaystyle \begin{align*} \theta = \textrm{arg}\,\left( z \right) + 2\,\pi\,n ...
  14. P

    MHB Effie's question via email about Complex Numbers

    First let's write this number in its polar form. $\displaystyle \begin{align*} \left| z \right| &= \sqrt{\left( -2 \right) ^2 + 2^2} \\ &= \sqrt{4 + 4} \\ &= \sqrt{8} \\ &= 2\,\sqrt{2} \end{align*}$ and as the number is in Quadrant 2 $\displaystyle \begin{align*} \textrm{arg}\,\left( z...
  15. P

    MHB Sava's question via email about solving complex number equations

    $\displaystyle \begin{align*} z^3 + 1 &= 0 \\ z^3 &= -1 \\ z^3 &= \mathrm{e}^{ \left( 2\,n + 1 \right) \,\pi\,\mathrm{i} } \textrm{ where } n \in \mathbf{Z} \\ z &= \left[ \mathrm{e}^{\left( 2\,n + 1 \right) \, \pi \,\mathrm{i}} \right] ^{\frac{1}{3}} \\ &= \mathrm{e}^{ \frac{\left( 2\,n + 1...
  16. P

    MHB Effie's question via email about a volume by revolution

    To start with, we should find the points of intersection of the two functions, as these will be the terminals of our regions of integration. $\displaystyle \begin{align*} 2\,x^2 &= x + 1 \\ 2\,x^2 - x - 1 &= 0 \\ 2\,x^2 - 2\,x + x - 1 &= 0 \\ 2\,x\,\left( x - 1 \right) + 1 \,\left( x - 1...
  17. P

    MHB Brenton's questions via email about volume by revolution

    Q5. Here is a graph of the region to be integrated and the line to be rotated around. First we should find the x intercept of the function $\displaystyle \begin{align*} y = 3 - 4\,\sqrt{x} \end{align*}$ as this will be the ending point of our region of integration. $\displaystyle...
  18. P

    MHB Divanshu's question via email about cylindrical shells

    Here is a sketch of the region to be rotated around the y axis. You first need to visualise this entire region being rotated around the y axis, to get a mental picture of what the solid looks like. Then you need to imagine that the solid is made up of very thin vertically-oriented hollow...
  19. P

    MHB Divanshu's question via email about a volume by revolution

    Here is a graph of the region to be rotated. Notice that it is being rotated around the same line that is the lower boundary. The volume will be exactly the same if everything is moved down by 4 units, with the advantage of being rotated around the x-axis. So using the rule for finding the...
  20. P

    MHB Jesse's question via email about volume by revolution

    Here is a sketch of the region to be rotated and the line to be rotated around. Notice that the volume will be exactly the same if we were to move everything up by 3 units, but with the advantage of rotating around the x axis. So we want to find the volume of the region under $\displaystyle...
  21. P

    MHB Nour's question via email about volume of revolution using cylindrical shells.

    Here is a sketch of the region to be rotated. To find a volume using cylindrical shells, you first need to picture what the region would like like when that area is rotated around the y axis. Then consider how it would look if that solid was made up of very thin cylinders. Each cylinder has...
  22. P

    MHB Kivindu's question via email about volume by revolution

    Here is a sketch of the region R and the line to be rotated around. Clearly the x-intercept of $\displaystyle \begin{align*} y = 3 - 3\,\sqrt{x} \end{align*}$ is (1, 0) so the terminals of the integral will be $\displaystyle \begin{align*} 0 \leq x \leq 1 \end{align*}$. We should note that...
  23. P

    MHB Kishan's question via email about volume by revolution

    We should first find the $\displaystyle \begin{align*} x \end{align*}$ intercept of the function $\displaystyle \begin{align*} y = 2 - 5\,\sqrt{x} \end{align*}$, as this will be the end of our region of integration. $\displaystyle \begin{align*} 0 &= 2 - 5\,\sqrt{x} \\ 5\,\sqrt{x} &= 2 \\...
  24. Z

    Java How to email using gmail smtp?

    Hi, I want to write a program to email using gmail smtp. I got following code from internet. import javax.mail.*; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; import java.util.Properties; /** 10 * Created by anirudh on 28/10/14. 11 */ public class...
  25. P

    MHB Kishan's question via email about an indefinite integral

    What is the $\displaystyle \begin{align*} \int{ \frac{54\,t - 12}{\left( t- 9 \right) \left( t^2 - 2 \right) } \,\mathrm{d}t } \end{align*}$ We should use Partial Fractions to simplify the integrand. The denominator can be factorised further as $\displaystyle \begin{align*} \int{ \frac{54\,t -...
  26. I

    Admissions Email professor 10 days after admissions interview?

    I had a skype interview with a professor in Canada for M.Sc. admissions. This was 10 days ago on April 20. The interview went okay. He said he would talk to the graduate coordinator, check my application and get back to me by the end of April. Monday, May 2nd would be the first working day after...
  27. P

    MHB Ross' question via email about a derivative.

    What is the derivative (with respect to t) of $\displaystyle \begin{align*} y = 16\,\left[ \sinh{(7\,t)} \right] ^3 \cosh{(7\,t )} \end{align*}$? One way to do this is to apply the product rule. To do this, we need to know the derivative of each factor. $\displaystyle \begin{align*}...
  28. P

    MHB 3600244's question via email about a derivative

    What is the derivative (with respect to t) of $\displaystyle \begin{align*} 15\log{ \left| \sec{ \left( 9\,t \right) } + \tan{ \left( 9\,t \right) } \right| } \end{align*}$? $\displaystyle \begin{align*} y &= 15\log{ \left| \sec{ \left( 9\,t \right) } + \tan{ \left( 9\,t \right) } \right| } \\...
  29. P

    MHB Effie's question via email about an indefinite integral.

    What is the indefinite integral (with respect to t) of $\displaystyle \begin{align*} 50\,t\cos{ \left( 5\,t^2 \right) } \end{align*}$? $\displaystyle \begin{align*} \int{ 50\,t\cos{\left( 5\,t^2 \right) } \,\mathrm{d}t } &= 5\int{ 10\,t\cos{ \left( 5\,t^2 \right) }\,\mathrm{d}t } \end{align*}$...
  30. P

    MHB Kamal's Questions via email about Implicit Differentiation

    Since we have this relationship between x and y, as the two sides are equal, so are their derivatives. We just have to remember that as y is a function of x, any function of y is also a function of x, with the inner function "y" composed inside whatever is being told to do to the y. So to...
  31. S

    Is It Appropriate to Use Salutations in Subsequent Email Posts?

    I noticed that almost every professor and departmental staff at any university only uses salutations (Dear xxx, etc.) in their first email post. In subsequent email posts in the same email thread, they do not continue to use salutations. Will it be considered rude if I, as a student, also use...
  32. P

    MHB Effie's question via email about Implicit Differentiation

    To perform implicit differentiation we must make use of the chain rule. Basically if you have a function composed in another function, its derivative is the product of the inner function's derivative and the outer function's derivative. All other rules (such as the sum rule, the product rule...
  33. P

    MHB Solve System w/ Gaussian Elimination & Partial Pivoting (Sufyan)

    We write the system as an augmented matrix $\displaystyle \begin{align*} \left[ \begin{matrix} \phantom{-}1 & 4 & \phantom{-}1 & 0 & \phantom{-}5 \\ \phantom{-}1 & 6 & -1 & 4 & \phantom{-}7 \\ -1 & 2 & -9 & 2 & -9 \\ \phantom{-}0 & 1 & \phantom{-}2 & 0 & \phantom{-}4 \end{matrix} \right]...
  34. P

    MHB Jamal's Q via email solving a system

    We can write the system in an augmented matrix as $\displaystyle \begin{align*} A = \left[ \begin{matrix} 2 & -2 & -1 & \phantom{-}0 & \phantom{-}6 \\ 2 & \phantom{-}3 & \phantom{-}2 & -5 &-14 \\ 0 & \phantom{-}5 & \phantom{-}2 & \phantom{-}2 &\phantom{-}1 \\ 0 & \phantom{-}0 & \phantom{-}2 & -3...
  35. P

    MHB Jamal's question via email about solving a system with a PLU decomposition.

    To start with, since $\displaystyle \begin{align*} A = P\,L\,U \end{align*}$, that means in our system we have $\displaystyle \begin{align*} P\,L\,U\,\mathbf{x} = \mathbf{b} \end{align*}$. Normally to solve for $\displaystyle \begin{align*} \mathbf{x} \end{align*}$ we would use inverses, so we...
  36. P

    MHB Emad's question via email about Inverse Laplace Transform

    The closest Inverse Laplace Transform from my table is $\displaystyle \begin{align*} \mathcal{L}^{-1}\,\left\{ \frac{2\,a\,s\,\omega}{\left( s^2 + \omega ^2 - a^2 \right) ^2 + 4\,a^2\,\omega ^2 } \right\} = \sin{ \left( \omega \, t \right) } \sinh{ \left( a \, t \right) } \end{align*}$ so we...
  37. P

    MHB Effie's question via email about Eigenvalues, Eigenvectors and Diagonalisation

    Effie has correctly found that the eigenvalues of $\displaystyle \begin{align*} A = \left[ \begin{matrix} \phantom{-}3 & \phantom{-}2 \\ -3 & -4 \end{matrix} \right] \end{align*}$ are $\displaystyle \begin{align*} \lambda_1 = -3 \end{align*}$ and $\displaystyle \begin{align*} \lambda_2 = 2...
  38. P

    MHB Question from Kamal about Gaussian Elimination via email

    I'm not sure where you're getting the idea that z = 2, as this is not correct. I'm assuming this is to be done without pivoting... Set up your augmented matrix: $\displaystyle \begin{align*} \left[ \begin{matrix} 2 & \phantom{-}1 & -3 & -5 \\ 1 & -1 & \phantom{-}2 & 12 \\ 7 & -2 & \phantom{-}...
  39. W

    How to use Business Email (Technical)

    Hi All, I recently started a new job and I was assigned a personal email address by the company, but I am clueless on how it works: The email is of the form : username@companyname.com I was told I can "log on to it" through Gmail. Anyone know how this works? I mean, how can I...
  40. H

    Best Free Email Provider for Importing Contacts and Sending Email?

    Recently Google decided to flood me with softcore porn. Enough. I tried about a dozen other free email providers. All I want to do is import my contacts and send email. I couldn't get it done. It was the usual software nightmare. Anyone have a recommendation?
  41. Lagraaaange

    Is it ok to email professor about final exam and grades

    Is it ok to email a professor asking them to confirm your grades to this point e.g. you send them all your homework grades and midterm grade in case of error and ask them about your final exam score? Would this be nagging and or condescending. Wouldn't want to hurt my image just before final...
  42. S

    Reference letter related email etiquette

    I've applied to a particular university for fall 2016 graduate admission. The deadline for my referees to submit the application is December 01. One of my referees is currently extremely busy and has asked me to request the graduate administrator to contact him regarding the reference letter...
  43. MarneMath

    Sending a thank you email after an interview

    I have been interviewing interns for our spring internship program and one of the candidates recently sent me an email basically reiterating what he considers his strengths, thanking me for the time to interview him, and letting me know that he appreciated the opportunity. Now, I know people...
  44. P

    MHB Yonglie's question via email about ratio test

    First, because the series is positive term, we don't have to worry about absolute values. Now $\displaystyle \begin{align*} a_n = \frac{2n + 3}{4n^3 + n} \end{align*}$ and $\displaystyle \begin{align*} a_{n + 1} &= \frac{2\left( n + 1 \right) + 3}{4 \left( n + 1 \right) ^3 + n + 1} \\ &=...
  45. T

    MHB A. Lahey Electronics: Email Delivery Times & Probabilities

    "An internal study at Lahey Electronics,a large software development company,revealed the mean time for an internal email message to arrive at its destination was two seconds. Further, the distribution of the arrival times followed a Poisson distribution. a.What is the probability a message...
  46. Benevito

    Is it ok not to reply to professor's email during weekends?

    After asking a professor about undergraduate research on Friday, I received a positive reply that very evening. The professor also asked me to send him my CV. Hovewer, it would take me some time to make it. Would it be ok to send the CV on Monday, or is it rude to take more time than him to reply?
  47. lonely_nucleus

    Calculators Can TI-84 calculator send text messages or email?

    Well the texas instruments ti-84 calculator is my favorite toy. I use it for anything I can from getting a girl to put her phone number in my calculator to programming. Is there a way to somehow add an external circuit that can make the ti-84 send text messages. I bet there would have to be a...
  48. V

    Is there any physicists i could email?

    I have so many questions about the universe so if there are any physicists(with a degree) i could email please tell me.
  49. S

    MHB Probability That Receipt Of Email 1 AND Email 2 Was Random

    An issue I’ll call Issue 1 arose and prompted Event A to occur. A few days after Event A occurred, I received a virus email I’ll call Virus Email 1. The content of Virus Email 1 referred to something that is a direct outcome of Event A. Therefore, Virus Email 1 is directly related to Event A...
  50. B0b-A

    Wildcard google-search to find email addresses of company?

    Is it possible to do a wildcard google-search to show all the email addresses in a company ? If I know an email address exists like ... john.smith@123company.com Is there some way of doing a wildcard google-search which will list all emails ... *@123company.com where * = wildcard...
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