The host sent across this message couple of days back:
Our Abuse department has received a report regarding malware being hosted on an account under your control. We have disabled site access for your account to prevent further complaints, and have provided a list of the reported content.
In order to remove the restrictions weâve placed, you must resolve the security issue and remove what malicious content was listed. Please note that repeated reports of malicious content on your account within 60 days of an initial notice will lead to further action being taken, including permanent suspension after failing to professionally clean the account.
We have also partnered with SiteLock, a website security monitoring tool for small and medium-sized businesses so we can provide you with any assistance to sign up for their service, or you can reach them directly at 111-111-1111.
Once you have taken steps to secure your account of the reported content, please reply back to this ticket to request review.
It, definitely, came to me as a surprise as I've been spending many weekends to keep the site' software up-to-date to prevent it from any SQL injection or something similar of that sort. Looking at the host's website and on internet I guessed that they have purchased a security software, deployed it and it has started flagging some of the websites, at their end, for no reason and they want us to follow the instructions from it now - good or bad, does not matter!
Had been following up with them and this is the latest response from them:
I apologize as this issue was not due to a malware issue, but rather it was due to a large volume of email being sent out from you account...
Well, that's very much possible which I'll change but that is not a malware for sure and one should have informed me, from admins of the host, before taking a decision but the harm is already been done - site was not reachable for some days.
Somethings are just not in your control and perhaps some are -- like change the host but will they also have similarly "skilled" set of people!
...I rest my case!