08-29-2008, 04:44 AM
I manage a small ISP, and I've been using greylisting for over a year (I have a home-grown implementation). In general, I'm happy with the results of greylisting, but there is one issue for which I haven't yet figured out a good solution.
The users at my site belong to a variety of mailing lists, many more than I'm willing to deal with as part of my sysadmin duties. Some of these mailing lists send out their emails through a group of servers, so that a they arrive with a variety of sender addresses. Because of this, some emails to any given user might get greylisted if he or she had never received anything from that particular sender address, and others come straight through because they are from sender addresses that were already used in the past to send email to this particular user.
This causes mailing list messages to sometimes arrive out of order for the given user, which is often confusing for them. I get lots of complaints about this.
This situation also occurs for users who are making online purchases or placing online orders. Sometimes the company on the other end sends emails through some sort of service which doesn't always use the same sender addresses. This can cause some of these emails to be greylisted and others not, thereby leading to more message ordering problems, which is another source of confusion for these users.
I know that I can manually whitelist any given mailing list (i.e., make its emails exempt from greylisting), but as I mentioned above, there are too many of these lists for me to manage in this way. And this is an even more prohibitive task if we take into account the emails that people get as part of the online transactions that I described above, since we are not normally aware of the sending addresses that these services use until after the message ordering problems have already occurred and have been reported to us.
Furthermore, most of our users don't want to have to notify us of their sometimes changing collection of email lists, nor do many of them want to have to learn about the concept of greylisting to begin with.
Therefore, I have to deal with an ongoing stream of complaints about sequences of messages arriving out of order. This is a productivity drain, since this is a small ISP with only a limited number of human resources.
So I'm wondering how other users of greylisting manage this message ordering issue.
Thanks in advance for any insights you all can offer.
The users at my site belong to a variety of mailing lists, many more than I'm willing to deal with as part of my sysadmin duties. Some of these mailing lists send out their emails through a group of servers, so that a they arrive with a variety of sender addresses. Because of this, some emails to any given user might get greylisted if he or she had never received anything from that particular sender address, and others come straight through because they are from sender addresses that were already used in the past to send email to this particular user.
This causes mailing list messages to sometimes arrive out of order for the given user, which is often confusing for them. I get lots of complaints about this.
This situation also occurs for users who are making online purchases or placing online orders. Sometimes the company on the other end sends emails through some sort of service which doesn't always use the same sender addresses. This can cause some of these emails to be greylisted and others not, thereby leading to more message ordering problems, which is another source of confusion for these users.
I know that I can manually whitelist any given mailing list (i.e., make its emails exempt from greylisting), but as I mentioned above, there are too many of these lists for me to manage in this way. And this is an even more prohibitive task if we take into account the emails that people get as part of the online transactions that I described above, since we are not normally aware of the sending addresses that these services use until after the message ordering problems have already occurred and have been reported to us.
Furthermore, most of our users don't want to have to notify us of their sometimes changing collection of email lists, nor do many of them want to have to learn about the concept of greylisting to begin with.
Therefore, I have to deal with an ongoing stream of complaints about sequences of messages arriving out of order. This is a productivity drain, since this is a small ISP with only a limited number of human resources.
So I'm wondering how other users of greylisting manage this message ordering issue.
Thanks in advance for any insights you all can offer.
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