The most common SMTP Servers are:

• Eircom subscription: mail1.eircom.net
• Eircom free: mail2.eircom.net
• UPC (ex NTL): smtp.upcmail.ie
• IOL Free: mail.iolfree.ie
• IOL Subscription: mail.iol.ie
• Vodafone at home: smtp.vodafone.ie
  
• Clearwire: smtp.clearwire.ie / mail.clearwire.ie
• Digiweb: smtp.digiweb.ie (note: not for use for digiweb hosting)
  
• Magnet: smtp.magnet.ie
• 3: mail-relay.3ireland.ie
• Imagine Broadband : mail.imagine.ie
  
• Perlico: mail.perlico.ie

The above server hostnames are subject to change by their ISPs. Please contact your ISPs technical support department or support section of their website to find out the address of your SMTP server if this is the case.