SMTP server rejecting my email address

SMTP server rejecting my email address

Hi

When i try to send emails from my iPhone the error message "Unable to send email: the sender address ' rosie@comms.xyz' was rejected by the server" appears.  I have tried connecting via POP and IMAP - same problem/error message.  Is this connected to the fact that my emails sent from desktop are going into spam?  I am trying to force Wordpress to allow a SPF key of longer than 192 chars (as when i click 'generate' in the admin panel the text is over 192 chars each time).

Poss two issues here, sorry!

Look forward to getting them both resolved?

Kindest,
Rosie