The SMTP Service represents one of the simplest means of sending text messages from within an application. Messages are sent as emails to the SMS Gateway from within your application.

Messages can be sent securely to one or more recipients, and messages can be optionally replied to, with delivery receipts provided automatically, should you wish to receive them. However, please note that the SMTP service does not support the same depth of functionality as the Web Service or HTTPS Connector.

There are four main email domains and variants that can be used to send your email to. Each main domain offers different email-to-SMS functionality with the sub variants allowing you to send Unicode messages or the defer option enabling emails to be generated, sent to us but not processed outside of defined hours (please contact us to set your out of hours times). You can limit the content of the email to a single SMS, as well as sending your chosen 11 characters (Originator) with the text message, rather than a phone number that is used for reply purposes.

The four domains are as follows:

sms.textapp.net unicode.sms.textapp.net defer.sms.textapp.net	Up to 918 (396 for Unicode messages) characters of your email (subject and body) will be sent out as one extended-length SMS, with a reply-path number to enable a recipient to reply
smsid.textapp.net unicode.smsid.textapp.net defer.smsid.textapp.net	Up to 918 (396 for Unicode messages) characters of your email body will be sent out as one extended-length SMS, with your choice of Originator taken from the first 11 characters of your email’s subject
sms160.textapp.net unicode.sms160.textapp.net defer.sms160.textapp.net	Up to 160 (70 for Unicode messages) characters of your email (subject and body) will be sent out as one regular-length SMS, with a reply-path number to enable a recipient to reply
sms160id.textapp.net unicode.sms160id.textapp.net defer.sms160id.textapp.net	Up to 160 (70 for Unicode messages) characters of your email body will be sent out as one regular-length SMS, with your choice of Originator taken from the first 11 characters of your email’s subject

Any message that is sent in excess of 160 characters will be sent (and charged for) in multiples of 153 characters. The recipient’s handset will join the constituent message parts together, and present the message as one extended length message.

When an email message is sent to the SMS Gateway, the gateway authenticates the email by checking the FROM address of the email. The email is accepted and processed if the FROM address matches an email address on the client’s account.

Additional security can be implemented by adding a PIN to the end of the phone number, delimited by a full-stop. When received, the email’s PIN, if provided, is checked against the client’s PIN for verification. Further security can be provided by locking down the IP addresses that we accept emails from.