Using different or changing 'from' addresses in email campaigns presents a complex set of deliverability considerations. While some sources suggest that using different 'from' addresses for different purposes (e.g., support vs. sales) is acceptable, the overwhelming consensus emphasizes the importance of consistency. Frequent changes can dilute sender reputation, confuse subscribers, trigger spam filters, and disrupt ISPs' ability to assess sender legitimacy. If changes are necessary, a gradual warm-up process, updating SPF/DKIM records, and carefully monitoring domain reputation are crucial. Utilizing subdomains or dedicated IPs can also help mitigate risks. A/B testing 'from' addresses is an option, but should be approached cautiously and monitored closely.