Hello! Maybe this is an outside the box question but, I would like to ask for some recommendations on email services that could be used along with ISPConfig in order to increase the delivery rate. Email is inherently a PITA, I though I had it handled by using Sendgrid as a relay service, but I'm finding more and more issues, not that the email get into SPAM, but that the receiver email company will prevent the message to reach at all. Any advice?
what do they give as the reason for not accepting the message? i have no idea of your setup, how long it's been running, or your own knowledge/experience level, so some of this may already be obvious to you / already done. the first things to do, check your sending ip's aren't on any blacklist. make sure there are correct PTR records for your mailservers. set your mailserver to use good RBL lists, (spamhaus etc), will stop you receiving a lot of spam in the first place, so will help cut down any sent back out as mailforwards. make sure virus/spam scanning is configured, this should already be in place if you followed a perfect server tutorial., although you may want to adjust the spam trigger levels. make sure every maildomain and mailbox account has a spamfilter level set. make sure every domain that can send mail from your server has SPF, DKIM, and DMARC records correctly configured in their dns zone. with all of that in place, there really shouldn't be any reason for other mailservers to refuse to accept mail from your server. it's a personal preference for me, but if your mailserver is separate to your webserver(s), you could block your webservers from making outbound connections to any destination on port 25, stops the webserver from being able to send spam out directly. wouldn't allow a webserver local postfix or sendmail/phpmail to relay through your mailserver either. would force all websites to send out mail using an authenticated email account, which means your mailserver or webserver can never be a source of spam for people with websites with you and email with someone else. and if someone who has both hosting and email with you has a site that starts spamming, it makes it much easier/quicker to find the source of the spam, and to block it without having to stop postfix / mailqueues for everyone.
Hi thanks for the response. I have gained some experience over the years, but yeah email has being an uncompleted issue for me. I handle most of my services and platforms. I had a notion that it was "easier/safer" to use a smtp relay service like Sendgrid, than building up some score based on my IP. I have tune PTR, SPF accordingly, I'm not very aware of DMKI and DMARC so I just leaved as enabled but as default maybe I'm missing some tune up there. I've studied the subject and tried to comply the most with the current setup I have (depending on a relay service). For the security part, I try to force smtp on all the applications, so no website have an open pass on delivery, but still good idea to segregate both. The idea of setting it all up with no email player in the middle is foreign to me so far.
