TO WHAT EXTENT IS IT POSSIBLE TO VERIFY THE EXISTENCE OF AN EMAIL ADDRESS WITH COMPLETE PRECISION?

Throughout the course of this post, we would want to talk about the issue of verifying the presence of email addresses with as much precision as possible. It will be explained to us why the basic verification command (verify) does not function correctly, and we will get familiar with an alternative command that may be used in its place: the rcpt to command. We will investigate the many replies that may be sent to rcpt to command and how they are interpreted. In conclusion, we have found a unique method to determine whether or not the server that has answered has provided a reliable response. Due to the fact that you are responsible for sending a large number of emails, the precision of the email validation is of utmost relevance for you, at least for two reasons: 1) the damage to your reputation; 2) the cost of your time and money. What is the issue with the verification of email addresses, and how can it be improved? In the event that we have a certain email address that we need to examine, let’s check the scenario. It would seem that we have successfully completed all of the first phases of communication with a target server in accordance with the SMTPS protocol. We were able to establish a connection to the server, we received a response to the helo command, and we sent our address from. At this point, we have made the decision to only check if the email address that we are validating really exists. If there is a command called verify that is built into the SMTPS protocol itself, then why don’t we simply use it and get an instant answer to the query that we have? It is important to remember that the purpose of the command verify was to give us with information on whether or not the email exists. As a result of our extensive expertise in this field, we have come to the realization that there are almost no servers in existence today that are capable of providing a reliable response to verify command execution. Therefore, the fact that we received a good response to verify does not necessarily imply that the email address that we find intriguing has ever existed. The method that is the most obvious and straightforward for determining whether or not an email exists does not function correctly. How are we able to verify that the email address is active? It would be more appropriate for us to utilize a different command from the SMTPS protocol rather than the verify command. The recipient address is included in the rcpt that we give to the command, which is the address that we need to cross-check. First, let’s get a better understanding of how to properly operate with rcpt. When we submit the rcpt to command to the server, we are informing the server that we have requested a certain location to which we would like to send an email. In order for us to send our letter to the address that was requested, this address must already be present in the system. The error number “550” will be returned by the servers in the event that this particular address does not exist. In light of the fact that we have received this error, Is it possible that the address does not exist? to have absolute certainty that this is the correct response to our inquiry? However, it is unfortunate that some servers may return a good answer of “250,” which indicates that your request has been approved, despite the fact that the email address may not exist. several further answers to the rcpt to command that were interpreted: Description of code 250: The desired mail activity is acceptable and has been accomplished 251 The user is not local; the forwarding will be done to the forward-path 421 domain. a transmission channel is being closed because service is not available. Requested mail action number 450 was not carried out: mailbox was unavailable 451 operation that was requested was canceled due to a local problem in processing 452requested action was not taken: there was not enough storage space in the system a syntax error of 500, the command was not recognized Error in syntax in either the parameters or the arguments 503 [RFC1846] Due to an incorrect sequence of operations, the 521 domain does not receive mail. Requested action number 550 was not carried out: mailbox was unavailable The 551 user is not local; kindly try the . The 552requested mail activity was canceled because the storage allocation was exceeded. Let’s look at some of the replies that may be sent. The server will return a “552” error if the email address that was provided is already full and you are unable to receive any more emails at this time. It is possible for the error “450” to occur if a certain email address is temporarily unavailable at this time. However, this does not necessarily imply that the address in question does not exist at all. For the purpose of determining whether or not an email address is present, it is necessary to take into account further negative answers. Before making a conclusion about whether or not the email address exists, there is one more instant that has to be taken into consideration. This is for the same reason that you are doing the check. For example, the message “the email address is full” that appears in the code 552 may be understood to mean that the email address is present. If, on the other hand, you plan to send an email to this particular address right away, then this activity is completely pointless. numerous conclusions to draw. The negative answer “550” to the rcpt to command or any other response that you perceive to be negative leads you to the conclusion that the email address that was sought does not yet exist. It is not possible to definitively take the affirmative answer “250” as evidence that the email address that was requested does in fact exist. To get a more specific understanding of the actions of the server in the event that a positive answer of “250” is received, you may use the following technique. The first thing you should do before beginning to verify a particular email address that you are interested in is to check a number of emails that are plainly not existent. A positive answer of “250” to a request for an email address that does not exist shows that the server does not conduct authentication of any email address at this level. As a result, the server does not ever send a negative response of “550” at this point. On the other hand, if the server gives a negative answer about a phony email address, this suggests that a positive response of “250” will also be considered trustworthy. yet again, we are back to the accuracy issue. It is important to take notice that the verification is accurate at this particular time. There will be a permanent appearance of new email servers, and the mail servers that are now in use will be removed. As a result of the constant updating of the DNS, it is now possible for an existing domain to cease to exist at any given moment. This is also something that may occur with the current email address. You are free to remove the email at any time, and it may be recovered at a later time. If you want to make sure that your database of email addresses is always up to date, it is recommended that you execute its verification: 1) on a consistent basis, and in particular 2) the smallest amount of time before sending an email. Now that you are aware of the issues, you have the option of arranging the verification of your mailing address on your own or making use of our professional services.

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