When the emails are not being sent (you mention receive) it is most often a server problem. The host may have disabled the php mail() function. This is why you won't find an easy answer to this problem on this forum.

If you host on your home computer, do check the firewall and virusscan settings.

Discovered problem is only with e-mails going to googlemail (which I use for my main mail). Not sure how to fix it though

Check your spambox within Googlemail. Do they show up there?

Nope

Resolved the problem. I was barking up the wrong tree with the googlemail thing.

Problem stemmed from me changing my hostname configuration on my linux setup. E-mail servers were not recognising the new hostname as being valid and so mail was being rejected.

Revised the hostname back to match my blogs domain and problem fixed :-)