Validate contact lists before sending. Review your contact list for obvious errors before launching a survey. Common issues include typos in domain names (e.g., "hotmial.com" instead of "hotmail.com"), non-existent addresses, and outdated contacts. Agile Research flags some invalid addresses during import but cannot catch all errors automatically.

Remove bounced contacts promptly. After a survey completes, review the contacts that bounced and remove or correct them before using the same list in future surveys. Repeatedly sending to addresses that have already bounced will trigger throttling faster and damage your sending reputation with email providers.

Avoid stale or purchased lists. Contact lists that haven't been updated recently are much more likely to contain invalid addresses. Lists sourced from third parties or assembled without direct opt-in carry particularly high bounce risk.

Use double opt-in where possible. Requiring recipients to confirm their email addresses before being added to your contact list ensures that addresses are valid and that recipients expect to hear from you. This reduces both bounce and complaint rates.

Use clear, relevant subject lines and sender names. Recipients are more likely to mark emails as spam when the sender or subject is unfamiliar or appears unsolicited. Use a recognizable sender name and a subject line that clearly communicates the purpose of the survey.

Vary your content across sends. Email providers analyze patterns in subject lines and body content. If previous sends with similar content generated high bounce or complaint rates, subsequent emails with the same content are more likely to be flagged as spam. Update your subject lines and email body when sending to new audiences or repeating surveys.

Consider sending to engaged contacts first. If you have a large contact list and are unsure of its quality, consider sending to your most recently active or engaged contacts first. This helps establish a positive sending pattern before reaching less certain addresses.

Test with smaller batches for new lists. When using a contact list for the first time, consider starting with a smaller batch to gauge bounce and complaint rates before sending to the full list. This limits the impact if the list contains a high proportion of invalid addresses.

Monitor the Survey Deliverability page after launch. Check your bounce and complaint rates within the first hour of sending, especially for large distributions or new contact lists. Early detection allows you to pause and address issues before throttling is triggered.

Act on warning notifications immediately. If you receive a complaint rate warning, investigate which survey triggered it and review the contact list quality and email content. Taking action at the warning stage prevents escalation to throttling.

Keep email customization within limits. Email messages with extensive customization, such as a high number of custom variables or very long message content, can significantly slow delivery throughput. To protect send performance, it is recommended that you limit the number of custom variables and the character length of email subject lines and body content.