SMS Subdomain for URL shortnening

@silvio6 

• It is a best practice, and often a technical necessity, to utilize distinct subdomains for different communication channels, specifically email and SMS.
• You can't use the same subdomain for both channels.
• A simple and effective strategy is to introduce a channel-specific prefix to the email subdomain. For example: As I mentioned in this thread, if your email subdomain is something like mktg.brand.com, and you have delegated it, you might pick a prefix appropriate for SMS URLs (e.g., sms.mktg.brand.com) to setup SMS subdomain.
• The fundamental reason for this separation lies in the management and protection of sender's reputation. Email Service Providers (ESPs) and mobile carriers maintain separate reputation scores for the domains/infrastructure used to send messages.
• Independent Reputational Impact: An important point to understand is that the deliverability and reputation issues associated with one channel do not typically cross over and contaminate the other.
• SMS Spam/Opt-Outs: High levels of spam complaints or opt-out requests generated through your SMS channel (due to unwanted text messages or poor list hygiene) will primarily impact your short code or messaging service's reputation with mobile carriers. These actions will not negatively affect the sender's reputation or the deliverability of your dedicated email subdomain.
• Email Spam/Blacklisting: Similarly, if your email domain faces blacklisting or a decline in inbox placement due to high spam rates, this reputational damage is isolated to the email infrastructure and will not compromise your SMS messaging performance or compliance.
• This isolation is a key protective measure, ensuring that a performance or compliance issue in one channel does not necessitate a complete domain migration across all communication platforms. By maintaining separate, clearly designated subdomains (and infrastructure), you can manage and troubleshoot each channel's deliverability and reputation independently.