Web Servers: Architecture and Security
Online MBA Degree
Email address validation/verification and clean user list.
EMAIL ADDRESS VALIDATION / VERIFICATION for sending bulk emails/newsletters:
| SN | Approach | Pros | Cons |
| 1 | Using javascript function. | Using Javascript method to validate email address is fast. And as it runs in client side, it has nothing to do with the network traffic. | Javascript method can validate email address syntactically not semantically i.e. it can validate both abcd@yahoo.com and abc@yahoo.com correct. So you can just validate the email address but cannot verify it. |
| 2 | By sending user a test mail to check whether the email address exist or not. | A test email can be sent to check whether the email address exists or not. When you send an actual email, the email server MUST reply with a bounce message if account doesn't exist. And the best thing is that most email servers respond immediately, so you get bounce message within seconds. During the registration the system validates not only the domain name and syntax of the email address but also checks that the mailbox is valid. | Many mail servers lie about mail boxes these days, so spammers cannot find out if a mailbox exists.
If you 'spam' hotmail or yahoo for example, they will start bouncing back your emails late (few hours or more), or not at all. |
| 3 | Using handshake method. | Using handshake method. That is, just reach up to the email address, connect with the mail server, get the welcome note and disconnect without actually sending a test mail. Faster than the approach#2. Can check for the misspelled address. Validate the domain name and user can see the result then and there. | This method depends highly on the network condition and may give incorrect or delayed or no result. DNS failure and grey listing can wreak havoc in this method. It doesn't prove that the person that completed the form actually owns that email address. |
Most Trusted And Widely Used Approach:
Double/Confirmed opt-in method:
In this method, when a user registers in your web site with his email address, send an email to the user with a link and ask him to click the link in order to confirm the email address is valid and authentic. In case, if you do not receive the response from such user (i.e. no link is clicked in the email), you can conclude that, that user is fake.
Advantages:
1. It reduces the probability of spam complaints. The confirmation process will help to ensure that people are only subscribed to your web site with their consent. Thus significantly reduces chance of email being ignored as “spam”.
2. Cleaner list -- people have to use their real email addresses in order to confirm their subscriptions in your web site. This also eliminates misspelled email addresses or those with typos.
3. Potentially more responsive subscribers (Higher response rate). Those who are genuinely interested enough to confirm their subscriptions/registration may also be more inclined to respond to your emails.
4. Safeguard against being “blacklisted” on DNSBLs by various anti-spam organizations.
5. Faster delivery.
6. Eliminates the possibility that an erroneous or problematic address may be added to your email list, i.e., someone signing up with a spamtrap or somebody else’s address, thus “poisoning” your email list.
7. Reduces the probability of an email/newsletter being bounced.
Disadvantages:
1. The main disadvantage is that many people may not understand your confirmation message or may not want to go through the extra step. This may cause the loss of subscribers.