Grey listing problems

[waterman34]

Hi all

I've had a few clients phone up saying that they haven't received some emails from a number of different customers so on inspection of the logs, I can see in the first instance of the message that the sender was grey listed, fine no problem but the next time the message was received the senders mail server now had a different IP address hence was again grey listed, this seems to have happened a few times now, especially when the sender was using a service such as claranet or blueyonder - has anyone found similar problems like this with grey listing?

The above brings me onto the next question, now I want to basically allow 'all' email from blueyonder to be accepted, so under spam settings and Grey List Safe IPs, to make blueyonder.co.uk safe, should I enter 'blueyonder.co.uk' in the 'IP of Host / Domain ' or the 'Reverse IP Lookup Matches' field?

{EDIT} In fact alot of my customers are now phoning up with problems that they are not received hardly any emails all to the point where I have had to disable the grey listing feature until I can find out whats going on, any advice support as the grey list feature seems to be causing alot of problems?

[rob]

This is one of the potential problems with grey listing and the only real way to combat is has you say, white list the affected servers. You should enter the reverse IP lookup in the format "*.blueyonder.co.uk". At present very few have had negative comments about grey listing as it has turned dire SPAM situations into managable and acceptable situations. Of course though not all the SPAM filters are siutable to most situations. As to the problem of the IP changing with different tries, this is fortunatly not a common problem as most re-attempts dont change IP. We are still open to suggestions on how we could try and combat this problem of course.

[waterman34]

Then maybe is has something to do with our setup somehow? Our backup mail server which is used for all the domains also uses grey listing with the same settings but is whitelisted on our primary mail server so there's no delay between them. Would this somehow affect things if for example the sending mail server gets a bounce from our primary greylisting and therefore trys the secondary mx record which is our backup, which also blocks it using the greylisting, would this create an issue whereby the sending mail server might just give up or do something weird!?

[Jack]

I have a question on this issue as well. It seems that some smaller domains don't retry at all after the first failure from greylisting. In this case if I want to bypass an entire domain such as "mydomain.com" what is the proper format and place to put it? I think it would be in the reverse lookup and I'm guessing the format would be "mydomain.com". Is this correct?

Thanks in advance, Jack

[rob]

Having grey listing on both your MX's shouldn't cause any extra problems. Generally if any domain is behaving correctly, they will retry later with the primary again. On our server we have a very good working bayesian filter and so we do not need the help of grey listing, however, to ensure we test all features it is enabled but set to the minumum; Temporary Fail=1, Temporary Allow=1440, Life Time=36. Even these settings reduced our SPAM by 80%.

To answer Jack's question, reverse IP is probably the best way, and you should use *.domain.com as the format. For white listing all the other filters, the SMTP sender address *@domain.com can be used.

[Jack]

I don't want to hi-jack the thread so forgive me if it seems so. I just have one more question on this for now. If I want to just add one address to the greylist bypass what's the proper syntax for that? For instance if I want to add someone@hotmail.com.

Thanks in advance, Jack

[rob]

Simply add a white list option and select the appropiate email address mode (sender or recipient depending on which one you want to white list), and enter the full email address.

[Jack]

I think you're talking about the spam filtering white list. Does this also bypass the grey list? Does this bypass all other filters?

[rob]

It causes mails to by-pass all the SPAM filters, but does not by-pass content filtering or antivirus filtering.