Eircom has apologised to its 350 thousand email customers - after they restricted access over a so-called 'intrusion'.
The company says access to eircom-dot-net will be back by this evening, having been suspended last night.
Eircom says they locked down their email service after detecting an intrusion on the service - and they've alerted the Data Protection Commissioner over the breach.
The company says there's no evidence to suggest any impact to their other systems or services, including customer data.
Eircom is strongly recommending that customers change their email account passwords today.
