Site-defined Address Validity Checks and Translations

Sites may wish to apply validity checks or translations to SMS destination addresses encoded in the recipient email addresses described in Directing Email to the Channel

• Strip non-numeric characters (for example, translating 800.555.1212 to 8005551212)

• Prepend a prefix (for example, translating 8005551212 to +18005551212)

• Validate for correctness (for example, 123 is too short)

The first two tasks can be done specifically with the DESTINATION_ADDRESS_NUMERIC and DESTINATION_ADDRESS_PREFIX channel options. In general, all three of these tasks, and others can be implemented using mapping tables: either mapping table callouts in the rewrite rules or by means of a FORWARD mapping table. Using a mapping table callout in the rewrite rules will afford the most flexibility, including the ability to reject the address with a site-defined error response. The remainder of this section will focus on just such an approach -- using a mapping table callout from the rewrite rules.

Let us suppose that destination addresses need to be numeric only, be 10 or 11 digits long, and be prefixed with the string “+1”. This can be accomplished with the following rewrite rule

sms.siroe.com      ${X-REWRITE-SMS-ADDRESS,$U}@sms.siroe.com
sms.siroe.com       $?Invalid SMS address

The first rewrite rule above calls out to the site-define mapping table named X-REWRITE-SMS-ADDRESS. That mapping table is passed the local part of the email address for inspection. If the mapping process decides that the local part is acceptable, then the address is accepted and rewritten to the SMS channel. If the mapping process does not accept the local part, then the next rewrite rule is applied. Since it is a $? rewrite rule, the address is rejected with the error text “Invalid SMS address”.

The X-REWRITE-SMS-ADDRESS mapping table is shown below. It performs the necessary validation steps for local parts in either attribute-value pair list format or just a raw SMS destination address.

X-VALIDATE-SMS-ADDRESS

! Iteratively strip any non-numeric characters 
   $_*$[$ -/:-~]%*  $0$2$R
! Accept the address if it is of the form 1nnnnnnnnnn or nnnnnnnnnn
! In accepting it, ensure that we output +1nnnnnnnnnn
   1%%%%%%%%%%      +1$0$1$2$3$4$5$6$7$8$9$Y
   %%%%%%%%%%       +1$0$1$2$3$4$5$6$7$8$9$Y
! We didn’t accept it and consequently it’s invalid
   *                $N

X-REWRITE-SMS-ADDRESS
    */id=$_*/*       $C$0/id=$|X-VALIDATE-SMS-ADDRESS;$1|/$2$Y$E
    */id=$_*/*       $N
    *                $C$|X-VALIDATE-SMS-ADDRESS;$0|$Y$E
    *                $N

With the above set up, be sure that DESTINATION_ADDRESS_NUMERIC option has the value 0 (the default). Otherwise, the “+” will be stripped from the SMS destination address.