Imitating Yahoo's AddressGuard using GMail

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Since some days ago, I’ve been moving all my mail from Yahoo! to GMail. Both have their advantages and disadvantages, considering that I use an e-mail client to store all my mail in my hard drive. With that, I mean that I don’t use the web interface. I download all my mail using POP3 access. My main reason to stay with Yahoo! is that I had been [ab]using AddressGuard intensely. AddressGuard was still free in the Spanish version of Yahoo! Mail, as opposed to the USA and other countries in which it was only available via Yahoo! Mail Plus, which costs like 20 or 25 USD a year.

There’s a flash demo in Yahoo’s website that explains what AddressGuard is and how to use it. Essentially, it’s a mechanism that allows you to have disposable e-mail addresses in a very convenient way. You have to create some sort of secondary Yahoo! ID which is used as a prefix for your disposable addresses, which have the form [email protected], replacing the .com domain by the relevant one. That secondary ID, which does not relate to your original Yahoo! ID is used as the prefix, and you could create suffixes quickly on demand. It’s like a web interface to qmail’s alias system.

You may know that one of the best ways of avoiding spam (probably the best) is not letting the spammers get your real e-mail address, and this is what AddressGuard facilitates you. Instead of giving people your real, true address, you gave them [email protected], and they couldn’t, from that, reach or know your [email protected] address. Mail sent to [email protected] is not accepted. In fact, only mail sent to valid suffixes is accepted and ends in the inbox of your Yahoo! mail account. So you have your Internet newbie friend John who asks you for your e-mail address and you give him [email protected]. In the moment John makes a mistake by sending you a chain-letter email, or is infected by a virus or malware which leaks that address to the public and you start receiving spam, you delete that suffix. You may inform John of what has happened, using the level of violence you consider appropriate, but you won’t receive more spam. This can also be used for other friends, websites, online stores, forums, mailing lists, etc.

I had abused the system so much that I had around 50 different suffixes in around 50 different places. This fact together with knowing that I wouldn’t have a similar system in GMail is the reason I considered to stay with Yahoo.

On the other hand, GMail had its own advantages. For example, GMail’s POP3 and SMTP access is secure. This meant that my username and password were going to be transmitted over an encrypted connection, detail that I like. It’s not about the e-mail message itself (I would use GPG for that), but about the username and password. Also, GMail doesn’t put ads at the end of the message like Yahoo does (unless you’re paying for Yahoo! Mail Plus), which is better when you send mail because having those ads at the end of the message looks very unprofessional. Also, GMail’s attachment size limits are higher. I don’t remember the exact numbers, but they are.

Anyway, I thought of a way to imitate Yahoo’s AddressGuard with GMail and then I moved all my mail. It was a long task, converting a handful of addresses each day until I finished. The system is not perfect for several reasons. I’ll explain it all.

I created 2 accounts. One was going to be the equivalent of Yahoo’s primary ID. The second one would imitate the secondary ID. GMail also has a suffix system, but it’s different to the one from Yahoo. In GMail, mail sent to [email protected] is also delivered to your address. This smells like a web interface to Postfix’s alias system. However, GMail doesn’t let you decide which suffixes are accepted, and it won’t hide your real ID. I chose to redirect every known [email protected] address to [email protected] using GMail filters. GMail doesn’t impose a limit in the number of filters. Caveats in this system, which may be important but so long they haven’t been for me?

  • GMail "To:" filters let you put the address there, but they will only look at the To and Cc e-mail headers. If someone includes you in their Bcc header, it won’t be forwarded. Note that the Bcc header won’t be present when you receive the message either. The same happens when someone doesn’t explicitly put your address in the message. This is typical in mailing lists. Mail is sent to the list address, but doesn’t mention who is receiving the message. This second case has a solution, which is to include an explicit filter so that mail sent to the mailing list (identified by the To header, words present in the subject or whatever) is also forwarded. The first case is unresolved. I mailed the GMail team so the system would use the Delivered-To header instead, which mentions your address, but so far I haven’t received a reply about it.

  • If an e-mail message is classified as Spam, it won’t hit the message filters. This means you have to check your mail using the web interface from time to time, just in case an important message is not filtered. Currently, there’s no way to disable GMail’s spam filtering features.

  • You can’t use the SMTP server and use any From header. If you use your primary ID account to authenticate to the SMTP server, the From header will be replaced. If you not only want to receive messages to [email protected], but also to send them, that is, use that address in the From header, you have to explicitly tell GMail to allow you, and you have to pass a simple verification process to do so.

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