How do HTML email size, TLD, attachments, and domain reputation affect deliverability and open rates?

Email deliverability and open rates are influenced by a multitude of factors, encompassing technical configurations, content practices, and sender reputation. HTML email size, while not directly impacting open rates due to ESP processing of conditional blocks, can affect deliverability due to longer loading times. Attaching files, especially PDFs, increases email size and can trigger spam filters. The choice of TLD has minimal impact if legitimate, although country-specific TLDs may enhance regional deliverability. Domain age and reputation significantly affect deliverability, with newer domains facing initial challenges. Sender reputation is crucial, impacted by sending volume, bounce rates, spam complaints, and engagement. Email authentication (DKIM, SPF, DMARC) is vital for verifying sender identity, and maintaining a clean IP reputation avoids blacklisting. HTML coding quality and the use of inline CSS also play a role, while optimizing email size for mobile users ensures better engagement. Analysing open rates by MX or recipient domain can help diagnose sending issues, and avoiding unsolicited or spammy attachments is essential for maintaining a positive sender reputation.

Several factors influence email deliverability and open rates. Larger HTML email sizes can negatively impact deliverability due to longer loading times and potential recipient frustration. Poorly coded HTML and unsolicited attachments can also trigger spam filters, reducing deliverability. A positive sender reputation, built through consistent sending practices, low bounce rates, minimal spam complaints, and strong engagement, is crucial. Older domains with established sending histories often have better reputations. Using reputable TLDs, implementing email authentication methods, and maintaining a clean IP reputation further enhance deliverability. Additionally, tailoring email size for mobile users, using inline CSS, and considering country-specific TLDs can improve engagement and trust with recipients.

Email deliverability and open rates are influenced by several interconnected factors. While HTML email size due to conditional blocks might not directly impact open rates as ESPs process them, attaching files, especially PDFs like shipping labels, can negatively affect deliverability by increasing email size and triggering spam filters. Domain age and reputation play a significant role, with newer domains facing initial challenges. Monitoring open rates by MX or recipient domain provides better diagnostic insights. Sending unsolicited or spammy attachments degrades sender reputation. Finally, the TLD's impact is considered negligible as long as it is legitimate, although local geoTLDs can be used for branding.

Email deliverability is significantly affected by several technical aspects. Exceeding Gmail's attachment size limits can cause rejections or spam filtering. Using invalid or misconfigured TLDs leads to email rejection due to routing issues. Certain attachment types, like executables, trigger spam filters. Implementing DKIM, SPF, and DMARC improves deliverability by verifying sender identity and reducing spoofing. Maintaining a clean IP reputation is critical, as blacklisting by services like Spamhaus severely impacts deliverability.