Why are my Sell emails being detected as spam?

Question

Some of my Sell emails are being detected as spam. How do I resolve this?

There are a number of reasons why your emails may be detected as spam, especially when sending emails in bulk. Possible reasons include:

The people you are sending the email to have strong spam filter settings on their email account or marked a previous email from you as spam.
Your email port settings need to be updated or adjusted, especially if you are currently using port 25 for outgoing mail. Port 25 is a known port for spam activity. If possible, change to port 443. For more information, see the article: Integrating email with Zendesk Sell.
Emails were flagged as suspicious due to the title of the email, for example, they contain obscure characters or titles, or the emails contain too many links.
Emails sent through Sell have embedded a small tracking pixel, which allows you to see who has opened them. Though very rare, this could cause an email to be flagged as spam by some providers.
A number of spam filters, such as Gmail and Yahoo, use content filtering to identify potential spam messages. Google's Bulk Email Guide offers some help on how to structure your emails to minimize the chance of them being flagged.