Why do POP3 connections take so long, but once the connection is established all is well?

In some configurations POP3 needs to generate random data for use by APOP authentications. This can lead to delays if /dev/random does not have enough entropy immediately available.

If you don’t need or want support for APOP, you can either compile SASL with --disable-checkapop, or you can disable APOP support in pop3[proxy]d at runtime by setting allowapop:0 in imapd.conf(5).

Otherwise, since there isn’t a strong need for high-quality random numbers with SASL, there are two options for dealing with this – link /dev/urandom to /dev/random. Alternatively, recompile SASL with --with-devrandom=/dev/urandom. It’s preferred to do the latter, as it avoids affecting other applications.