Some emails never reach recipient, most do

Important Account Related emails

[The_Hat]

Sometime ago I built a web app that automatically emails an image that is proof of their advertising purchase. The system has a short message about this being their proof for their advertisement,, etc etc.. In the email I specify the reply address as being an address in our core domain while the email is actually sent via phpMail on our third party host from a domain NOT the same as the reply address I specify..

Everything works great, everybody receives their email with out issue EXCEPT for a couple entities.

I did take a look into the ip address being black listed and found one result.. BARRACUDA..

I am asking if anybody can give me some advice on the best rules of thumb for getting emails past filters (I know that is a loaded question) or any information about BARRACUDA, i.e. what their place is in the industry, what email programs use their service, etc...

[lammert]

Barracuda offers a SPAM firewall solution which sits in between the Internet and incoming mail servers. It is a system used by companies and maybe some ISPs as a first line SPAM defense.

I have no idea however how they fill their IP database. Maybe they use some message heuristics, but it is also possible that the database is filled with reports from users. The website of Barracuda should give you more information about their listing and de-listing procedures of IP addresses.

[Hoople]

Is the image a GIF? Many large companies blocked GIF's in general or animated GIFs when they became a viri ditribution container recently (late '08?)

Barracuda's are a hardware IP filtering appliance that operate at the edge of larger customer's networks. They work from a central SPAM sender database initially but do have a local user whitelisting mechanism. To verify if you are in the central database [barracudacentral.org ]

Messages with high spam scores are automatically deleted on the Barracuda server. They ARE NOT sent to the user for whitelisting.

Messages with moderate-to-high spam scores are sent to a Quarantine Inbox on the Barracuda server. Users receive an email notifying them that they have these messages in their Quarantine Inbox.

Messages with low-to-moderate spam scores are tagged as suspected spam delivered to their Inbox. Outlook newer versions will move these to the 'Junk Mail' folder. With no changes on installation this feature is enabled by default in Outlook 2002 (Office XP) and newer.

There are tools to check a message's SPAM grade, you may wish to investigate them and tune your messages based on the tools recommendation(s). A few are listed here [emailexpert.org ]

[The_Hat]

The image is a jpg, and I also send them a link to the original pdf version as well.

Thanks for the reply Hoople this is some of the data I was looking for, very helpful.

[Hoople]

A few apps email failures I've troubleshot over time had a minor occurrence of poor SMTP implementation.

The more common of the two was not queing messages and retrying make for failures. This happens when the recipient's mail server is either TarPitting [en.wikipedia.org ] or Greylisting [en.wikipedia.org ]. Both never accept the message on it's first submission.

The other minor failure cause was missing required fields in the message that the recipient's mail server wanted. Reply-to and Sent (both client created fields) were two that I saw. The funny thing was it was a one way paging service!

[txbakers]

This is a serious issue and one you can't solve. If an ISP blocks you, you are hosed until you contact them and try to wade through their tech support to explain your situation.

we've been blocked, at one time or another, by Yahoo, MSN, Fuse.net, Knology.com, Bellsouth.com, SBCGlobal.com, Baracuda and one or two others.

We've managed to fix it each time. Baracuda was particularly nasty to work with. Arrogant bast***s. If you are on their list they consider you the scum of the earth, period.

i started sending emails as follows with a custom header:
Mailer.AddCustomHeader ("Sender: [e-mail]");

(with the real address and real domain of course).

This is what the NY Times does when you email an article. it shows up as "From: [e-mail] On Behalf Of ......."

That helps a little.

[Hoople]

Many non-human email 'clients' (and a few poorly coded open source ones) fail to follow RFC 2822 standards. Within RFC2822 is "The only required header fields are the origination date field and the originator address field(s). " More at [ietf.org ]

HOWEVER: almost all email clients used by humans add many more fields. Some anti-spam measures take this into account and test for them. From: To: Date: are some of the fields.

OK, so you're wondering which to add? Test with a human used client. If mail goes through compare headers to the failing app/sender. One at a time add in a header seen only in the successful email. Usually this takes only 2-3 tries before finding the stumbling point.

Watch the IP's as sometimes the IP seen externally is NOT what you think it is. I have seen cPanel on Centos Linux not put the Exim mail server on the same IP as Apache when there are more than one IP per server. Use a free email account to check IP.