I'm assisting someone with their small business's Google Apps account. They're having a big problem sending and receiving emails...in that sometimes they aren't doing either. It's not all their email, just a portion of it, but sometimes they don't receive the email that other people have sent them, and sometimes other people don't receive the email my client sends out.

After looking it all over, I found that an SPF record in their domain registrar/web hosts DNS settings wasn't including Google, and had another typo. Since then I've switched what was providing DNS altogether and things seem to have improved, but it's not clear yet.

My question is this: what can I do for them going forward? They're naturally scared that they've already missed some business and that other people think they haven't been as prompt in their replies as they actually have been. They also appear to be getting spam messages from old accounts in their systems that don't even exist anymore, so I assume that someone is spoofing some of their addresses.

Do I look into DMARC? I've only come across that recently and I'm not sure I entirely understand how it works.

I'm not just asking for them, either. I've recently discovered that some of my outbound emails were not delivered because my domain was marked my my web host for spamming. Of course, this happened without any notice to me, no bounce back notifications, and no way for me to know which emails did not get sent. This disturbs me greatly, as I'm worried that I've lost business over this. I'm considering moving all my email handling away from my web host (Bluehost - actually my client's web host too) to someone else. As it is, I'm just using GMail to check a POP3 account on their servers, but now I'm thinking of going with Google Apps or Office 365, but I have no idea if that will help anything.

Anyway, sorry for the rant. I'm just frustrated. I get that spam is a problem, but I can't imagine that my output ranks with even the lowest level spammer, and the content certainly doesn't. In the end, I would be far less upset if I had known what was happening, but there was absolutely no indication, and that worries me greatly.