![With no email in outbox: Failed to send some messages. Negative SMTP reply 501 5.1.3 Bad recipient address syntax · Issue #1286 · thundernest/k-9 · GitHub With no email in outbox: Failed to send some messages. Negative SMTP reply 501 5.1.3 Bad recipient address syntax · Issue #1286 · thundernest/k-9 · GitHub](https://user-images.githubusercontent.com/18624555/45620724-1d003a80-ba7e-11e8-9e38-e99c95f5e3d6.jpg)
With no email in outbox: Failed to send some messages. Negative SMTP reply 501 5.1.3 Bad recipient address syntax · Issue #1286 · thundernest/k-9 · GitHub
![Bad recipient address syntax when sending to an email ist | Thunderbird Support Forum | Mozilla Support Bad recipient address syntax when sending to an email ist | Thunderbird Support Forum | Mozilla Support](https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2015-10-23-16-40-24-3121c0.png)
Bad recipient address syntax when sending to an email ist | Thunderbird Support Forum | Mozilla Support
![SMTP Protocol Error: 501 5.1.7 Bad sender address syntax when sending mail from our printer through Nethserver - Support - NethServer Community SMTP Protocol Error: 501 5.1.7 Bad sender address syntax when sending mail from our printer through Nethserver - Support - NethServer Community](https://community.nethserver.org/uploads/db8506/original/3X/0/a/0accf4f0818d60d070a6d47e1a6ead6fcb60f103.png)
SMTP Protocol Error: 501 5.1.7 Bad sender address syntax when sending mail from our printer through Nethserver - Support - NethServer Community
![SMTP Protocol Error: 501 5.1.7 Bad sender address syntax when sending mail from our printer through Nethserver - Support - NethServer Community SMTP Protocol Error: 501 5.1.7 Bad sender address syntax when sending mail from our printer through Nethserver - Support - NethServer Community](https://community.nethserver.org/uploads/db8506/original/3X/6/0/6032135db52684bcd27cca1d9992238af976c488.png)