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Thanks IMIronMan, that's very useful information, appreciate your help.
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Thanks IMIronMan, that's very useful information, appreciate your help.

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Our client suddenly started to received hundreds of email warnings, receipts, returned notifications etc. The notifications seem to come from a myriad of sources globally.<br />
<br />
We first checked the PC for virus activity using NOD32 and Malwarebytes but found no infection. We checked all running processes and found nothing unusual.<br />
<br />
Checking the date/time of the notifications shows that they continue 24/7 even when the PC is switched off, thus we have kind of ruled out the PC as being a source of SPAM.<br />
<br />
We installed Spamfighter which removes about 1/2 the notifications automatically, which still leaves a huge amount to be deleted each day, but of course this is only masking the problem.<br />
<br />
The email address is their main contact so it is &quot;enquiries@xxxxxxxxx.org.u<wbr />k&quot; (xxxxxxxxx replacing their domain name) so I'm wondering if their email address is being used by a maliceous party.<br />
<br />
I'm out of ideas what to do next to try find and halt the source, thus if anyone has any suggestion what to try next, it would most appreciated.
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Our client suddenly started to received hundreds of email warnings, receipts, returned notifications etc. The notifications seem to come from a myriad of sources globally.

We first checked the PC for virus activity using NOD32 and Malwarebytes but found no infection. We checked all running processes and found nothing unusual.

Checking the date/time of the notifications shows that they continue 24/7 even when the PC is switched off, thus we have kind of ruled out the PC as being a source of SPAM.

We installed Spamfighter which removes about 1/2 the notifications automatically, which still leaves a huge amount to be deleted each day, but of course this is only masking the problem.

The email address is their main contact so it is "enquiries@xxxxxxxxx.org.uk" (xxxxxxxxx replacing their domain name) so I'm wondering if their email address is being used by a maliceous party.

I'm out of ideas what to do next to try find and halt the source, thus if anyone has any suggestion what to try next, it would most appreciated.

hundreds of returned email warnings received

Microsoft Outlook is a personal information manager from Microsoft, available as a part of the Microsoft Office suite. Although often used mainly as an email application, it also includes a calendar, task manager, contact manager, note-taker, journal, and web browser.

Outlook

Various techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) vs. not rejecting all spam (false negatives) - and the associated costs in time and effort. Anti-spam techniques can be broken into four broad categories: those that require actions by individuals, those that can be automated by email administrators, those that can be automated by email senders and those employed by researchers and law enforcement officials.

AntiSpam

An email client, email reader or more formally mail user agent (MUA) is a computer program in the category of groupware environments used to access and manage a user's email. A web application that provides message management, composition, and reception functions may internally act as an email client; as a whole, it is commonly referred to as webmail. Likewise, email client may be referred to a piece of computer hardware or software whose primary or most visible role is to work as an email client. Email clients can also have other systems, like calendars, notes and contact managers.