February 2023 Summaries

SMTP is the protocol that sends email from clients to outgoing servers and relays it between mail servers, with different ports commonly used for submission and relaying. Port 25, the original SMTP port, is now primarily intended for server-to-server relaying because many providers block it for message submission due to historical spam abuse. Port 587 is the officially recognized and broadly supported default for secure email submission using STARTTLS, while port 2525 is a reliable TLS-capable fallback when 587 is unavailable, despite lacking formal standardization. Port 465 remains in use by some legacy services for SSL-based SMTP but is generally discouraged unless required, and port 1025 may serve as a last-resort submission alternative. Major providers typically use port 587, although Gmail and Yahoo also support 465 for SSL, and deliverability depends not only on port selection but also on factors such as infrastructure, email content, complaint rates, and performance monitoring.

An email blast is a single mass message sent simultaneously to many recipients, typically for promotions, announcements, product updates, newsletters, or event invitations, whereas an email campaign is a targeted sequence designed to nurture relationships over time. Email blasts can provide broad, inexpensive, and easily measurable reach, but irrelevant or obviously impersonal messages may lead to deletions, spam complaints, and disengagement. Effective use relies on building permission-based subscriber lists rather than buying contacts, segmenting audiences by factors such as demographics and purchase history, personalizing content, using clear subject lines and calls to action, and creating visually organized, brand-consistent designs. Appropriate email marketing tools help track open, click-through, conversion, unsubscribe, bounce, spam-complaint, and forwarding rates, while ongoing optimization through A/B testing can improve subject lines, layouts, and calls to action. Typical benchmarks cited include open rates of 15–30%, bounce rates near 2%, and conversion rates of 2–5%, though results vary by industry.

Mailtrap Email Sending supports Handlebars templates to dynamically create email subjects, plain text, and HTML from JSON data, enabling personalization without modifying an application’s codebase. Supported features include basic variable and nested-object replacement, unescaped HTML output with triple braces, conditional rendering through `if`, `unless`, and `else`, iteration over arrays or objects with `each`, and context changes with `with`. Examples demonstrate how these helpers can personalize subscriber messages, display item lists with fallback content, simplify access to nested user information, and produce a complete order-confirmation email containing product, shipping, and delivery details. Templates can be tested through Mailtrap by adapting an Email Sending integration request to use the Testing API endpoint, adding the target inbox ID, and using the inbox-specific API token to preview rendered emails in a sandbox.

Email open rate measures the percentage of recipients who open a campaign and serves as an early indicator of email performance, typically calculated using unique opens divided by total recipients or, more accurately, delivered recipients after excluding bounces. Average rates across campaigns can be calculated by averaging individual campaign rates, while click-to-open rate measures the share of openers who also click a link and helps assess content relevance. Opens are usually tracked through invisible pixels, though blocked images and privacy settings can reduce accuracy, while trackable links and read receipts have their own limitations. Performance varies by email type, industry, timing, region, device, list quality, and content, with transactional emails generally receiving more opens than marketing messages. Improving open rates involves using recognizable personal sender names, brand identifiers such as BIMI, concise and relevant personalized subject lines, audience segmentation, and avoiding spam-like language or excessive formatting. The post also recommends monitoring deliverability, bounce and spam rates, and testing authentication, SMTP routing, template rendering, spam scores, and email content before sending campaigns.