Spam, or junk mail, now accounts for over 85% of all email traffic in Ireland.
The figures are based on the monitoring of more than 13 million email messages, sent to over 1000 domains, during the month of July.
Limerick based web company, Elive, says 'spammers' are constantly adapting the measures they use to clog up email accounts.
It says there has been an rise in the number of PDF (Portable Document Format) attachments, meaning the size of an average spam mail has increased by around 80%.
If somebody opens an attachment of this size, traffic levels and bandwidth allocations are affected.
The volume of spam in July far outweighed the number of viruses that were in circulation. According to the data from Elive, viruses accounted for less than 1% of email traffic.