Email Client Compatibility: Different email clients (like Gmail, Outlook, Yahoo) render emails differently. This can cause inconsistencies in how your email appears to users. Coding Standards: Emails need to be coded using HTML and CSS, but not all HTML/CSS properties are supported by every email client. Image Blocking: Many email clients block images by default. Marketers need to use alt text for images to ensure that the message is still conveyed. File Size: Large emails can take longer to load and may be truncated by some email clients. Spam Filters: Various factors can trigger spam filters, affecting email deliverability.