June 2025 Summaries

Verifying email addresses is crucial for maintaining low bounce rates and preserving sender reputation, as fake or mistyped addresses can infiltrate lists through various means. Email verification APIs, such as Emailable, ZeroBounce, NeverBounce, Kickbox, BriteVerify, Bouncer, and Mails.so, offer solutions by validating syntax, checking MX records, and verifying SMTP servers to ensure deliverability. Each API has unique features, such as data enrichment, integrations, and compliance with standards like GDPR, and caters to different needs, from hobbyists to large enterprises. While verification APIs can significantly improve email list hygiene, they are not infallible and should be used alongside other measures like CAPTCHAs and double opt-in emails to enhance accuracy and engagement rates. Resend, an email platform for developers, provides various tools and expert support to optimize email deliverability and recommends a combination of verification and additional methods for best results.

The text discusses how Domain-based Message Authentication, Reporting, and Conformance (DMARC) policies work with subdomains, emphasizing the importance of understanding the organizational or parent domain, which DMARC relies on to determine policy information. When a mail server receives a message, it undergoes a policy discovery process to apply the correct DMARC policy, checking first the specific domain in the "From" header and then the organizational domain, while intermediate subdomains are skipped. Subdomains typically inherit the organizational domain's DMARC policy unless a specific policy is published for a subdomain, with the optional "sp" tag allowing for different treatment of subdomains without individual records. The guide suggests starting with a simple DMARC policy for the entire domain and gradually tightening it, using the "sp" tag only at the organizational level, as it is ignored if applied to subdomains.

Pedro Gomes has joined the team at Resend to work on distributed systems and enhance the company's email infrastructure. Previously a software engineer at Firmly, he developed a serverless infrastructure handling over 300,000 requests per month, and at iFood, he contributed to authentication features for 60 million users. Pedro's journey into software began in college, where his love for logic and puzzles led him to switch majors from Computer Engineering to Computer Science. He is drawn to Resend for its culture and values and finds inspiration in nature and travel. If not programming, Pedro would have pursued psychology, and he emphasizes the importance of balance and self-care for career success. His favorite tool is Cursor, which aids in debugging and testing, and he dreams of one day living in Vila Velha, Brazil.

Dedicated IP addresses in email sending can play a role in deliverability but are not a one-size-fits-all solution, as their effectiveness depends on the sender's specific circumstances. While a dedicated IP can provide greater control and is suitable for high-volume, consistent senders with expertise in deliverability practices, shared IPs are often more beneficial for senders with moderate volumes, inconsistent patterns, or those still establishing their reputation. This is because shared IPs leverage the established reputation of trusted senders, which can enhance inbox placement without the complexities of IP warming. The true driver of email deliverability lies in domain reputation, which is shaped by sender behavior, engagement, and adherence to best practices, unlike IP reputation which is becoming less relevant due to advancements like IPv6 and frequent provider changes. Ultimately, the choice between dedicated and shared IPs should align with sending habits, goals, and familiarity with email best practices, emphasizing the importance of building a strong domain reputation. Resend offers support and guidance in navigating these decisions and strategies for long-term success.