To be able to send email via 3G Broadband modems, you must either use SMTP authentication with your mail or domain hosting company or use a VPN connection to a business network. If you have neither of these, then it is possible to configure your email client, such as Outlook or Outlook Express to use your own 3G services providers own SMTP server.

Outbound SMTP Server Settings for sending Email

Three 3G Data SMTP Servers:
smtp-mbb.three.co.uk
smtp.three.co.uk

Vodafone 3G SMTP Servers:
smtp.vodafone.net
send.vodafone.net

T-Mobile 3G SMTP Servers:
smtp.t-email.co.uk

Orange 3G SMTP Servers:
smtp.orange.net
smtp.orange.co.uk

O2 SMTP Servers:
smtp.o2.co.uk

Virgin SMTP Servers:
mail.virgin.net
smtp.virgin.net