Here are easy-to-implement tips that will improve server communication and transmission efficiency. Use anti-spam tools Since a wide range of error messages are connected to firewalls blocking sender addresses, a smart way to troubleshoot these challenges is by making sure your IP is not used for spamming. Start running regular anti-spam checks by using tools like Mailwasher or Zerospam. In this article, you can learn more about measuring your email deliverability and how email testing tools work.
Limit sending volumes Most ISPs have a croatia telegram database threshold to how many emails they let senders send per hour — once you cross it, SMTP errors will show up and message delivery will be compromised. Although it’s natural for marketers to set high sending volume KPIs, be sure to keep the number of emails you send at per hour or lower. Double-check sender-recipient data The bulk of transmission errors appear because a recipient’s email is no longer valid.
To make sure users don’t enter wrong emails when they sign up to the mailing list, add an email verification tool to the website — this helps point out website visitors who enter invalid emails on purpose or make accidental typos. Other than that, double-check if the address in the “To” field matches the one in the subscriber base. Change ports Email ports visualization. Email ports visualization. Source: Mailtrap As mentioned above, few spam-strict ISPs block all messages coming from the sending port since too many spammers use it to share unwanted and irrelevant messages.