[sqwebmail] corrupted user name in email address

[sq sub]

I have been using sqwebmail 3.3.7 for some time and it's ok. 

after upgrading to v4.0.2 I now get corruption in the user name part of the 
email address when I send an email. it looks like random stuff then the last 
two characters are ok then followed by the @and domain. 

The system is running on redhat 7.2 (yes it's old!) 

does anyone have the same issue? 

DEREK