This is slightly off-topic but since I bet alot of people here use DNSMadeEasy to host, it would be the best place to post this.
I'm currently using DME as my DNS host for failover. I recently enabled their backup mail service and they changed my MX records with their servers which were needed so that my mail could be held by them in case my smtp server goes down.
Well, unknown to me they started employing anti-spam techniques on my mail as it passed through! I already have 2 separate spam filtering servers so I noticed fairly quickly that legitimate email was being blocked. Apparently dnsmadeeasy greylists all mail which is a pretty hefty step to take if you know anything about spam filtering. There is NO way to disable this or control it.
I am extremely frustrated because I view DNS hosting on par with ISPs. ISPs don't filter your web content. DNS should filter DNS requests, nor should they filter your mail (with no recourse).
Of course my recourse is to stop using them and use someone else. But I wanted to check here and see what everyone thought - or if anyone could recommend a service that is just a responsive and doesn't cost $1000 a month
As a backup MX, their server should have a higher priority number assigned to it and your production MX should have a lower number. Most mail servers will attempt the MX with the lower priority number, higher priority, first. It is spammers who will go after the higher numbered servers while ignoring the lower priority numbered servers. Perhaps you could check to make sure that the appropriate priority numbering has been applied to your MX records.
Your alternative is to not use a backup MX at all. Let the sending mail server spool the mail until it is able to deliver it. Most of the time the sending server will try for about 3 days. At least that way the sender will see NDR's while the mail is waiting. As long as your email server comes back up within 3 days, you'll be ok. This is the way things are supposed to work with SMTP.
DNS Made Easy backup email services have always done greylisting (at least for the last 6 years that I have used it).
You have to think about it. $1 per month for backup email... for all of your users.... Are they supposed to queue your domain with the 5 million emails of spam that come through every month for that?
It would be nice if they offered users the option to pay more so they do not have greylisting (maybe $1.00 per user per month or something like that).