You can send messages up to 200MB in size per email on your Virtual Office (VO) webmail.
If you would like to send attachments that are larger than this, you can use Drop File on Storage instead.
Note that you may not be able to send larger email attachments if you are using other email clients that have their own attachment limit (e.g. Ms Outlook 2010 only allows up to 20MB of total attachment size).
You may also not able to send larger email attachments to recipients who use other email services with smaller attachment limits. If your attachment is too large to be received by your recipients, you can Drop File|drop the files to them instead.
There is no limitation on how many attachment you can send via webmail. However, it is recommended to keep the number low as most email providers have receiving attachment limits.