Where did you install Firefox from? Help Mozilla uncover 3rd party websites that offer problematic Firefox installation by taking part in our campaign. There will be swag, and you'll be featured in our blog if you manage to report at least 10 valid reports!

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

An error occurred while sending mail. The mail server responded: 5.1.2

dneil
dneil
more options

I have a center where two employees are using Thunderbird and they are the only ones getting this message. It just started today. No changes were made. The error is- An error occurred while sending mail: The mail server responded: 5.1.2 The address specified is not a valid RFC-5321 address. h81sm2028729ywc.40 - gsmtp.

I have verified all setting and verified the email address they are attempting to send to. They are able to recieve incoming mail but cannot reply. If they use gmail they can send and reply just fine.

Others in the center are using outlook at they are able to send just fine.

I have a center where two employees are using Thunderbird and they are the only ones getting this message. It just started today. No changes were made. The error is- An error occurred while sending mail: The mail server responded: 5.1.2 The address specified is not a valid RFC-5321 address. h81sm2028729ywc.40 - gsmtp. I have verified all setting and verified the email address they are attempting to send to. They are able to recieve incoming mail but cannot reply. If they use gmail they can send and reply just fine. Others in the center are using outlook at they are able to send just fine.

All Replies (1)

NicholasB54
NicholasB54
more options

Theres a lot of chatter about this over at the gmail support forum https://productforums.google.com/forum/#!msg/gmail/2tK2fR7yW-k/9Gk3L49QFCcJ

A couple of people finding solutions - worth a read .. but it's long. Not just Thunderbird affected, Outlook and several other clients too