sendmail blocked by some ISPs

jck has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I've been using sendmail to send registration emails to users on our site, and had no problem until recently. Now, certain users (notably people on comcast.net, yahoo.com, and verizon.net) are not receiving emails from our server.

has anyone else encountered this problem? I know quite a few of you recommend using Mail::Sendmail - does that simply use the sendmail function, or might it possibly fix this problem?

appreciate any feedback, since many of my users are getting frustrated (as am I!!)

one additional piece of information - i suspected that the mails might be going to spam filters, but i tested it using my own comcast account, and it simply never comes through! nothing in the spam, or anywhere. i'm checking with a yahoo account (don't have verizon to check it)

thanks,
janaki

Comment on sendmail blocked by some ISPs

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Re: sendmail blocked by some ISPs by chargrill (Parson) on Feb 04, 2007 at 02:09 UTC
Do you have an email account setup to receive mail bounces? Chances are likely that those ISPs have determined you to be a spammer and have thus blacklisted your server. See if you can't capture some of those bounce emails that are coming back (as they most assuredly are) and see what they have to say about your emails - some ISPs even give you a link to their policy, along with instructions on how to remove yourself from their blacklists (assuming you're a legitimate mailer, which in your case it sounds like you are). --chargrill `s*lil; $=join'',sort split q; s;.;grr; &&s+(.(.)).+$2$1+; $; = qq-$_-;s,.,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$,$/)` [download]	[reply] [d/l]
Re^2: sendmail blocked by some ISPs by jck (Scribe) on Feb 04, 2007 at 02:17 UTC
i do have an email account from which i am sending the emails, and nothing is bouncing back - that's what seems so strange.	[reply]
Re^3: sendmail blocked by some ISPs by chargrill (Parson) on Feb 04, 2007 at 03:27 UTC
In that case I would recommend sending test emails to other accounts on other systems that don't bounce ( ;) ) and carefully inspect the "reply-to:" and "from:" headers to make sure they are what you think they are. I currently work for a company that regularly get determined to be a spammer (I really think we're not, honest!) and it's always a careful read of the bounces to determine who has us (and more importantly why we are) blocked. It's possible that by directly interfacing with sendmail that the "From:" header of your sent emails are showing up differently? Or perhaps you have email aliases (/etc/aliases) sending that mail to that account directly to /dev/null? Perhaps a .forward file you weren't aware of? Also try sending a test email to your bounce handling account to make sure you can receive at least that :) --chargrill `s*lil; $=join'',sort split q; s;.;grr; &&s+(.(.)).+$2$1+; $; = qq-$_-;s,.,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$,$/)` [download]	[reply] [d/l]
Re: sendmail blocked by some ISPs by Sagacity (Monk) on Feb 04, 2007 at 03:11 UTC
Hello, Head to http://www.senderbase.org. Use their interface to enter your server domain name or IP numbers and see if your server is listed anywhere as a spam server. Though you may not be a spammer, others who use the same server may be. Hence the advice of the chargrill is solid. It's a shame that good things are so easily taken over by people who have ill intentions(Spammers). The rest of us end up jumping through hoops wasting time and money trying to accomplish what should be simplistic enough. Another thought is to double check your email address format. The @ needs to be escaped (\@), especially if you are reading the list from a file. Good Luck!	[reply]
Re^2: sendmail blocked by some ISPs by Marza (Vicar) on Feb 04, 2007 at 07:29 UTC
God I hate them. Senderbase blacklisted us once and would not give us the reasons why. Their only advice was to stop sending email.	[reply]
Re: sendmail blocked by some ISPs by nacredata (Sexton) on Feb 04, 2007 at 03:46 UTC
Good advice given already. It is harder by the day to send legitimate email, especially in bulk. Many, many thing to check. Content of messages. Reverse DNS of envelope sender. SPF record. Also begin to think creatively about alternatives to email as a content delivery mechanism.	[reply]
Re: sendmail blocked by some ISPs by clinton (Priest) on Feb 04, 2007 at 10:48 UTC
Also, make sure that you have an SPF record, and that your SPF record includes your server. SpamAssassin, for example, does an SPF check by default.	[reply]
Re: sendmail blocked by some ISPs by jck (Scribe) on Feb 04, 2007 at 05:06 UTC
thanks so much to all for the great suggestions.........i'm going to investigate these possibilities........oddly, one of my scripts from the same domain, using the same From: address as on the script that is failing works just fine(!?!?)....haven't sorted out what's different - looks identical. they both have subject headers, so that's not it....ugh! but, nevermind - i do appreciate the assistance from your most-knowledgeable monks!	[reply]