Forum Moderators: LifeinAsia
I'm currently running two very email intensive business in Mexico and overzealous spam filtering on behalf of client's systems is really starting to be a drag on my business.
The odd part is, my emails are being filterd despite that fact that they are responses to client inqueries and are in no way mass mailings, unsolicted junk, or cold calls. This is a recent problem growing bigger by the day and now consumes about 20% of my outbound email. Fast responses are of the essence so it's really starting to hurt.
I was horrified to see that prodigy.com.mx. Mexico's biggest ISP as of today is filtering my emails which would be the kiss of death.
Is there anything that can be done, not to trip the spam wire? What factors do spam filters use to determine wether an email is legit?
(Who ever said spam was harmless? It causes business to build fortresses around their systems to the point that legit emails can't get through.)
Have you set up the reverse DNS entries for your mail servers.
Is there a corresponding A record in your DNS that matches the reverse DNS?
(And, no the clients weren't filtering my email specifically but there is obviously some new commonplace filter that I'm triggering for some reason, but thanks for the input.)
For example say a spam from an email server comes in from IP address 101.102.103.104, it may say it comes from security.microsoft.com
A spam filter checks to see if the IP address is genuine by doing a reverse DNS lookup on 101.102.103.104. If that reverse DNS says anything other than security.microsoft.com then it is likely to trigger it as spam.
It is a very bad idea to set up an email server without setting up reverse DNS for it.
I don't want to be brutal, but that really is something that the administrator of an email server should know. If they don't know that, then they're not really qualified to be administrating an email server. If they made that mistake then they are quite capable and likely to make more mistakes with your precious customers email in future.
I'd consider outsourcing your email to a specialist email company rather than trying to operate it in house without the right skills.
Email servers are very inexpensive, much cheaper than web hosting.
Thanks for the info. Yes, that seems fundamental. Actually, I use on of the biggest hosts on the net andthey should know better so I'm assuming it was an oversite. They corrected to problem so I hope that all will be well.
Thank you very much for the very helpful advice!
Additionally, how would this impact someone who is forced to use their ISP's SMTP server to send mail, as opposed to their web hosting company's, which is where the from address is hosted. I say this because some ISP's won't allow any other SMTP server's to send mail through their network.
A "PTR record" which was configured this way:
b*****m@r3***z:~$ host -t a mydomian.com
mydomian.com has address 123456789(myip)
b*****m@r3***z:~$ host -t ptr 123456789(myip)
123456789(myip).in-addr.arpa domain name pointer mydomian.com
I get messages in the retuned mail such as "may be forged" "No esta permitido el SPAM" (spam not permitted) and "unverified".
Is PTR the same as reverse DNS? Is there more they should be doing?
I recently had to get RDNS on my site since AOL suddenly started rejecting my emails - but what was worse, the error message AOL's servers gave was completely inaccurate and said I was being rejected by member complaints.
Fortunantly, AOL has a 24-hour 800 number professionals can call to clear up such issues. They were actually quite nice to deal with, did a search for any member complaints on my IP, found none, and assured me that if I got RDNS working the problem would resolve.
Once RDNS was in place, my backlog of messages cleared out within hours.
Note that many "verification" or "keyword based" spam filters (particularly poorly written ones) will reject your emails, but there's absolutely nothing you can do about that.
