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Check If Email Exists

github.com

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Re: Check If Email Exists

#191

Post by sildur »

femto113 wrote: post #114
profmonocle wrote: post #105

Earlier quoted context omitted.

A non-marketing example: We were onboarding a large new client to our SAAS product. This process involved creating accounts for all of their employees (tens of thousands) and sending emails with an activation link. (Where they'd be able to set up their password.) Our system sends these emails in batches, and as soon as the first batch went out we got an alert from our monitoring system that our bounce rate was surgin…

If they're checking using SMTP's VRFY command then it's actually considered a best practice for the server to always reply with a 252 "cannot verify" since otherwise it can be used to fish for valid addresses.

But... I could also fish for valid addresses by trying to send an email and waiting for a bounce...

Re: Check If Email Exists

#192

Post by golergka »

ganafagol wrote: post #154
profmonocle wrote: post #105

Earlier quoted context omitted.

A non-marketing example: We were onboarding a large new client to our SAAS product. This process involved creating accounts for all of their employees (tens of thousands) and sending emails with an activation link. (Where they'd be able to set up their password.) Our system sends these emails in batches, and as soon as the first batch went out we got an alert from our monitoring system that our bounce rate was surgin…

This is clearly trying to solve a non-technical problem with technical means. The root problem is that AWS cancels you with too high bounce rate. The obvious solution is to talk to some AWS representative to at least temporarily not cancel you after explaining the situation. If AWS does not let you talk to them, then that's where the problem lies, not in some not cleaned up email list. It's terrible to spend a lot of…

> This is clearly trying to solve a non-technical problem with technical means.

Isn't that the whole point of what most of us are doing?

Re: Check If Email Exists

#193

Post by alibarber »

blackearl wrote: post #52
reid wrote: post #30

Earlier quoted context omitted.

I bought a new car a few years ago and I was unable to enter my .life email address into the SiriusXM registration form in the car. Had to use a .com address :(

I specifically bought a cheap .org since some companies have trouble with lesser known TLDs

I have a hyphen in the domain (.com) I use for personal email (it's shorter, just my initial and surname) and I still have had problems in some places with that - it's so frustrating.

Re: Check If Email Exists

#194

Post by e12e »

sildur wrote: post #191
femto113 wrote: post #114

Earlier quoted context omitted.

If they're checking using SMTP's VRFY command then it's actually considered a best practice for the server to always reply with a 252 "cannot verify" since otherwise it can be used to fish for valid addresses.

But... I could also fish for valid addresses by trying to send an email and waiting for a bounce...

Yes, and you could be eg: graylisted. Or server could accept all an silently drop. Or rate limit.

It's sad that VERIFY is basically dead due to spam. In the olden days, you might have been able to use finger - but it's also dead for (among other) similar reasons.

The spam cat and mouse game leads to quite silly situations for benign actors.

For some mx's you might be able to designate some ips as trusted, and do real verify for those.

Re: Check If Email Exists

#195

Post by LeonM »

jhugo wrote: post #125

The accepts_mail test seems flawed; a domain with no MX records can still accept mail (the spec requires an MTA to connect to the IP address in the A/AAAA record of the domain part of the mail address in this case). All MTAs that I’m aware of support this, and it’s moderately common on personal domains with a single self-hosted MX, rare as those are these days.

Interesting! I did not know this

For those wondering, this is actually specified in rfc5321 section 5:

  If an empty list of MXs is returned,
  the address is treated as if it was associated with an implicit MX
  RR, with a preference of 0, pointing to that host.
https://datatracker.ietf.org/doc/html/rfc5321#section-5

Re: Check If Email Exists

#196

Post by relix »

Cyberdog wrote: post #8

Could someone spell out a use case for this? One that comes to mind would be validating that a mailing list doesn't have any outdated email addresses in it, but couldn't that be determined by just checking for a bounce when a message is sent to it? I tried to sign up for SiriusXM the other day, and though I could create an account with my .pro email address, I couldn't actually sign up for service with that same addr…

I receive a lot of fake user signups on the web tool I publish for free. These users (bots?) sign up using fake email addresses, but putting a captcha does not help much. I send a confirmation email to these users to make sure they exist, but if the email address does not exist, sending that confirmation email hits my account's deliverability (spam) score as it generates a bounce which my email sender provider does not appreciate.

For example, I've received multiple warnings from Intercom that I need to improve deliverability of my email, or they will ban my account. Ironically one of the suggestions is to use confirmation emails - but that's exactly where the problem is for me.

A tool like this helps me to weed out a ton of these undeliverable email addresses to avoid sending emails that will hit my spam score.

> checking for a bounce

So in my case, generating that bounce is exactly what I need to avoid in order to make sure my account remains in good standing.

Re: Check If Email Exists

#197

Post by r1ch »

relix wrote: post #196
Cyberdog wrote: post #8

Could someone spell out a use case for this? One that comes to mind would be validating that a mailing list doesn't have any outdated email addresses in it, but couldn't that be determined by just checking for a bounce when a message is sent to it? I tried to sign up for SiriusXM the other day, and though I could create an account with my .pro email address, I couldn't actually sign up for service with that same addr…

I receive a lot of fake user signups on the web tool I publish for free. These users (bots?) sign up using fake email addresses, but putting a captcha does not help much. I send a confirmation email to these users to make sure they exist, but if the email address does not exist, sending that confirmation email hits my account's deliverability (spam) score as it generates a bounce which my email sender provider does n…

If a tool like this works for you, what stops you from sending validation emails yourself?

Re: Check If Email Exists

#199

Post by ericmay »

relix wrote: post #196
Cyberdog wrote: post #8

Could someone spell out a use case for this? One that comes to mind would be validating that a mailing list doesn't have any outdated email addresses in it, but couldn't that be determined by just checking for a bounce when a message is sent to it? I tried to sign up for SiriusXM the other day, and though I could create an account with my .pro email address, I couldn't actually sign up for service with that same addr…

I receive a lot of fake user signups on the web tool I publish for free. These users (bots?) sign up using fake email addresses, but putting a captcha does not help much. I send a confirmation email to these users to make sure they exist, but if the email address does not exist, sending that confirmation email hits my account's deliverability (spam) score as it generates a bounce which my email sender provider does n…

I think what this is telling you is that users don’t value giving you their email address for your free tools. They know why you want their email address, and they don’t want that, but they do want your tools. Maybe it’s time to charge money for those tools or change models? Maybe not give access until the email address is confirmed? Worth considering I guess. Idk the details. I do this all the time. Ads and malpractice have made giving out your email address risky business. If a user can give you a fake email and get what they want without giving you anything (subject to your ads or whatever you’re using their email for) that’s the logical thing for them to do.

Not judging or anything though I know my tone might seem that way.

Re: Check If Email Exists

#200

Post by tealpod »

Cyberdog wrote: post #8

Could someone spell out a use case for this? One that comes to mind would be validating that a mailing list doesn't have any outdated email addresses in it, but couldn't that be determined by just checking for a bounce when a message is sent to it? I tried to sign up for SiriusXM the other day, and though I could create an account with my .pro email address, I couldn't actually sign up for service with that same addr…

I use to have a active product DearEle.com an email reminder service. There was a feature to cc everyone in email, which is used by spammers to send junk products to everyone. The source emails were all fake. Email check prevent fake emails.
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