What causes Gmail's 'sender's email address uses abnormal characters' error?

Marketer from Email Geeks warns about Cyrillic 'a', and potential issues with 'I' and 'l' characters.

Email marketer from Stack Overflow explains that certain special characters, while technically allowed in the local part of an email address according to RFC specifications, may not be supported by all email providers. Using these characters can lead to compatibility issues.

Email marketer from Reddit shares that copy-pasting email addresses from websites can sometimes introduce hidden or unusual characters that are not immediately visible but can cause validation errors. They suggest manually typing the address.

Email marketer from Super User discusses the limitations of older systems. It claims that older mail systems may not support non-ASCII characters, leading to the error message. Modern systems generally handle this well now.

Marketer from Email Geeks asks if the sender address has been analyzed for anything out of the ordinary, like characters other than letters and numbers, when Gmail throws an error about abnormal characters.

Email marketer from Email on Acid suggests that the encoding of the email address might be incorrect. Specifically, it mentions that if the encoding is not UTF-8, then extended characters may cause problems.

Email marketer from Litmus shares that the error may be related to sender reputation, especially if the domain has recently been used for spam. Although unusual characters may trigger it, the root cause could be deliverability problems.

Email marketer from Google Support responds that using invalid or unsupported characters in the 'From' address is a common cause. Addresses should adhere to standard email formatting, using only allowed characters.

Email marketer from Mailjet explains that this error can be triggered by characters that are not part of the standard ASCII set. This includes accented letters, Cyrillic characters, or other special symbols. They advise checking the sender's email address for any such characters.

Expert from Spam Resource (Laura Atkins) explains that character encoding issues are a frequent cause. Some systems may misinterpret or fail to support specific character sets, leading to the 'abnormal characters' error. Encoding mismatches during the transmission or storage of the email address can result in the same problem.

Expert from Word to the Wise discusses the importance of cleaning up data in email addresses to ensure they are valid. It explains that if someone is getting the 'abnormal characters' error, it is likely due to the fact that email addresses that contain characters that aren't supported.

Documentation from IETF addresses the use of internationalized email addresses (addresses containing non-ASCII characters). While the standards exist, support can be inconsistent, and systems might not handle these addresses correctly, leading to errors.

Documentation from RFC Editor specifies the syntax for email addresses, including the allowed characters in the local part (before the '@' symbol) and the domain part. It clarifies which characters require quoting and which are explicitly disallowed.

Documentation from Microsoft explains that Exchange Online has specific limits and requirements for email addresses, including restrictions on the length and characters allowed in the local part and domain. Exceeding these limits or using unsupported characters can cause issues.